History Main / TwoDunIt

* This trope is rare in ''Series/MidsomerMurders'', but it does happen in "The Creeper", where the killers turn out to be a mother and daughter-in-law killing to protect a family secret.

** In "Claws Out", Madeline Saunders emotionally blackmails Perry Fleming into committing the first two murders for her, then commits the third one herself.

* One of the endgame reveals in ''VisualNovel/SpiritHunterDeathMarkII'' is that ''both'' Himeko Douryou and Michiho Kinukawa (or at the very least, [[KillAndReplace facsimiles of them]]) are the Departed that had kickstarted the spirits' reign of terror in Konoehara Academy to begin with, and picking both of them as the Departed in Kazuo's final deduction is the key to avoid getting the bad ending.

* One of the endgame reveals in ''VisualNovel/SpiritHunterDeathMarkII'' is that both Himeko Douryou and Michiho Kinukawa (or at the very least, [[KillAndReplace facsimiles of them]]) are the Departed that had kickstarted the spirits' reign of terror in Konoehara Academy to begin with.

* In ''VideoGame/MasterDetectiveArchivesRainCode'', one case has three primary suspects, but investigating the crime proves that none of them had the opportunity or ability to have killed the victim on their own. It turns out that this is because all three of them had colluded to carry out different elements of the murder as revenge for the victim killing a mutual friend six months prior, and getting away with it because of her family connections.

* ''Literature/{{Discworld}}: In ''Literature/{{Maskerade}}'', the major break in the case happens when Granny realizes there are two Opera Ghosts. One Opera Ghost is the hapless but good Walter Plinge, who used the Ghost to hide out under the opera house and do some other mysterious but not evil things. The other is Salzella and actually killed the dead opera members.

A less crowded version of EverybodyDidIt. Compare LotsaPeopleTryToDunIt, where multiple characters make separate attempts on the life of the victim.

** ''VideoGame/DanganronpaAnotherEpisodeUltraDespairGirls'': The was between kids and adults in Towa City was set up by Monaca Towa and AI Junko Enoshima, the latter disguised as Shirokuma and Kurokuma.

* One episode of ''Series/{{Castle}}'' has Castle competing with Beckett's RomanticFalseLead over who can solve the murder first, with each man focusing on one particular suspect. Beckett's the one who realizes that ''both'' suspects did it. They weren't working together, and had no idea the other one had done anything, they just both wanted the guy dead. Esposito tells Beckett it was generous of her to let both the guys win.

* ''Series/AmericanVandal'': The main characters wonder about the possibility in season one that more than one person was responsible for vandalizing the teachers' cars. Near the ending, they come to the conclusion that the most likely culprit, Christa, worked together with her boyfriend to do it, since she had her leg broken at the time. While she deleted the footage of the crime, her boyfriend did it.

* ''Series/{{Columbo}}'': This is the final reveal of ''Double Shock''. The episode shook up the [[ReverseWhodunit normal Columbo formula]] by showing the murder as normal and then a bit later revealing the murderer is one of a pair of identical twins, leaving the viewer uncertain which of the two did it. As the presence on this page indicates, it turns out they worked together on the murder.

* Many episodes of ''Series/CriminalMinds'' contain the reveal that the unsub is working with a partner, sometimes only near the end of the episode. It's also [[InvertedTrope inverted]] in some episodes, where acts that are "clearly" performed by groups or partnerships turn out to be committed by a single person (either with a split personality or some other psychosis that makes ''them'' believe someone else is involved).
* The Blue Paint killer in ''Series/{{CSI}}''. The first ep has the believed killer escaping execution due to more bodies being found, then he dies at the end. In the later ep, more cases popped up, and the group realized the executed man was just the apprentice. The guy captured in that episode was the real main killer. Both men did the crimes, though.

* In ''VisualNovel/AceAttorneyInvestigationsMilesEdgeworth'', a contradiction arises from initially missing this in case one.

** ''Literature/EvilUnderTheSun'': Supposedly Christine and Patrick are in a dysfuctional marriage and Patrick is carrying on an affair with Arlena, who turns up as the murder victim. In fact Christine and Patrick are quite HappilyMarried, and evil, as they collaborated together to kill Arlena.

** In book 1, a werewolf proves responsible for most of the murders due to being trapped in a house full of potential victims during the full moon, but Adam Stalker, a member of the influential [=DeFerrier=] family who was operating under an alias was responsible for the deaths of Councillor William Blackstone and later his wife Katherine.

* In ''Literature/WingsOfFire'', Tsunami initially assumes that the dragon killing Queen Coral's unhatched daughters is the same one who tried to kill her, herself a daughter of Coral. It turns out, however, that the killer of her sisters is an enchanted statue created by [[TheDeadGuyDidIt Orca]], while Whirlpool was the one who tried to kill her.

* In ''MasterDetectiveArchivesRainCode'', one case has three primary suspects, but investigating the crime proves that none of them had the opportunity or ability to have killed the victim on their own. It turns out that this is because all three of them had colluded to carry out different elements of the murder as revenge for the victim killing a mutual friend six months prior and getting away with it because of her family connections.

* In ''LightNovel/SwordArtOnline'', the perpetrator of the "Death Gun" killings in Gun Gale Online is revealed to be two people: someone controlling the in-game avatar, and a real-world accomplice who murders the player at the same time the avatar is killed to simulate the effect of a "magic gun that kills you in real life." But the real twist is that the government investigation afterward reveals there was a third partner in the loop who managed to evade authorities.

[[folder:Films -- Live-Action]]
* After the killer Santa Claus's identity is revealed in ''Film/ToAllAGoodnight'', it is shown to the audience that there is also a second one.

* Subverted in the first ''Film/ScaryMovie''. There are three separate killers all adopting the Ghostface persona. The first two are [[DepravedHomosexual two gay teenagers]] (although one of them is in denial about it) working together, while the "real" killer is a cop ObfuscatingStupidity who kills the former two for trying to upstage him.
* [[PlayingWithATrope Played with]] in ''Film/{{Psycho II}}'', wherein Lila Loomis and (initially) her daughter Mary are trying to drive Norman Bates back into insanity and murder by impersonating his seemingly long-dead mother (i.e. the source of his troubled mental state), while Emma Spool simultaneously commits a series of murders and claims to be Norman's actual mother. Ultimately, Mrs. Spool [[CollidingCriminalConspiracies kills]] Lila, Mary tries to kill Norman based on the mistaken assumption that he was actually responsible for the murders (and [[DramaticIrony becomes the main police suspect for them herself as a result]]), and Norman finally rejoins the fun by killing Mrs. Spool and resuming his life as a slasher.
* Used in ''Film/HellNight''. A bit of an odd example as the legend that surrounds the setting tells about one "deformed guy hiding in the house", and doesn't explain who the second deformed guy is.
* In the sex comedy ''Video Vixens'', a film-within-the-film, an X-rated ''Dragnet'' parody, involves a serial rapist who is actually identical twins; one would go out and rape someone while the other is seen in public doing something mundane as an alibi. The next night they'd [[TwinSwitch switch places]]. (Yes, despite the description, it's a comedy.)
* It is revealed two thirds into ''Film/JustBeforeDawn'' that the fat redneck psycho killing the cast has an equally fat psycho twin, and they work together in getting rid of people trespassing their family's territory.

* ''Film/MurderMystery'':
** Nick's original theory has Charles and Suzi conspiring (which they are, but unsuccessfully).
** Then he theorizes it's Grace and Tobias, which is half right.
** The actual killers are Juan and Grace.
* Subverted in ''Film/HotFuzz''. At first Nicholas Angel suspects the ObviouslyEvil local supermarket manager Simon Skinner of being behind the string of mysterious deaths, but he has a waterproof alibi. Just when Angel realizes that there must be more than one killer, he's attacked by Skinner's brutish thug, who tells him to rendezvous at a castle after believing Nicholas to be disposed of. Once Nicholas gets there, it turns out that in fact [[EverybodyDidIt almost the entire town is in on it]].
* ''Film/BloodAndBlackLace'': There are two people under the featureless mask at separate times Massimo killed some of the women, and Cristina killed the others to draw the police's attention away from him.
* In ''Film/BlackRat'', it turns out there are actually two different killers wearing the rat mask: Akura's sister Akane, and CreepyCrossdresser Kengo. [[spoiler:At the end of the film, after Akane and Kengo have both been killed, Misato dons the mask to kill the last survivor Saki.]]

* This was one of Creator/AgathaChristie's favorite twists. Many of her novels and short stories had the murderer turn out to be a man and a woman in a SecretRelationship who either pretended to dislike each other or not know each other, and then use that to create alibis and opportunities for each other.
** She first used it in her very first novel, ''Literature/TheMysteriousAffairAtStyles''. Alfred Inglethorp and Evelyn Howard pretend to hate each other, but they are secretly in cahoots to kill Emily Inglethorp (Alfred's wife and Evelyn's boss).
** ''Literature/TheyDoItWithMirrors'': Lewis and Edgar--secretly father and son--collaborated on the murder, with Edgar HoldingBothSidesOfTheConversation while Lewis stole off to do the deed.
** ''Literature/EvilUnderTheSun'': Supposedly Christine and Patrick are in a dysfuctional marriage and Patrick is carrying on an affair with Arlena, who turns up as the murder victim. In fact Christine and Patrick are quite HappilyMarried, and evil, as they collaborated together to kill Arlena.
** ''Literature/DeathOnTheNile'': Linnet and Simon are a honeymooning couple, with Jaqueline the WomanScorned stalking them. It turns out that Simon and Jacqueline were in cahoots from the beginning to kill Linnet so that they'd get their hands on her money.
** ''Literature/ThirdGirl'': Andrew Resnick and his wife Mary conspired to kill Andrew's old girlfriend Louise, because "Andrew Resnick" is actually an impostor and the real Andrew's old lover from back in the day, Louise, is basically the only person alive who can identify him as a fake.
** ''Literature/DeadMansFolly'': George and Hattie, a married couple, conspired to kill multiple, people, including the real Hattie (George's wife is an impostor), and two other people who knew of their crime.
** ''Literature/TheMurderAtTheVicarage'': Anne Protheroe and Lawrence Redding separately confess to the murder of Anne's husband in order to paint themselves as a pair of StarcrossedLovers, when in truth they carefully planned the crime together so that both would have an airtight alibi and be cleared as suspects.

* This trope is rare in ''Series/MidsomerMurders'', but it does happen in "The Creeper", where the killers turn out to be a mother and daughter-in-law killing to protect a family secret.
* In ''Series/DeathInParadise'', this turns out to be the solutions in''The Blood Red Sea, The Complex Murder, and Murder at the Polls''.
* One episode of ''Series/{{Castle}}'' has Castle competing with Beckett's RomanticFalseLead over who can solve the murder first, with each man focusing on one particular suspect. Beckett's the one who realizes that ''both'' suspects did it. They weren't working together, and had no idea the other one had done anything, they just both wanted the guy dead. Esposito tells Beckett it was generous of her to let both the guys win.
* Many episodes of ''Series/CriminalMinds'' contain the reveal that the unsub is working with a partner, sometimes only near the end of the episode. It's also [[InvertedTrope inverted]] in some episodes, where acts that are "clearly" performed by groups or partnerships turn out to be committed by a single person (either with a split personality or some other psychosis that makes ''them'' believe someone else is involved).
* Like the movie it's based on, the killer in the first season of ''Series/{{Scream}}'' turns out to have been been two people. This is first suspected by the characters when the killer of the first season is revealed, as they were seemingly attacked by the killer in a previous episode. The surviving killer then becomes the new BigBad of the next season, their motive being revenge for the death of their accomplice.

* In ''VideoGame/{{Persona 4}}'', there are actually ''three''. One copycat, one pawn who thought he was ''defeating'' the killer (while actually creating new victims) and then the original killer that orchestrated the whole scheme. There's also a ManBehindTheMan, who had nothing to do with the killings but caused them indirectly by empowering the original killer.

* In ''VideoGame/ParadiseKiller'': The full investigation eventually reveals that there were two separate plots to murder the Council that happened on the same night, completely unaware of each other. The player can unveil both, or play favorites to spare characters they sympathize with.

* In ''VisualNovel/NineHoursNinePersonsNineDoors'', the True Ending of the game reveals that the mastermind behind the Nonary Game, Zero, is actually ''two'' of the game's participants. Though Santa is actually TheDragon to Zero/Akane. Also, Ace masterminded the first Nonary Game and is the reason Akane did this one.

* A possible theory about the truth of the Rokkenjima Mansion massacre in ''VisualNovel/UminekoWhenTheyCry'' is that the events are caused by two teams working independent of each other, one planning and one opportunistic. It eventually turns out that this is indeed the case- Beatrice/Yasu was the one who planned the DeadlyGame, but when everyone won and lived, it was Kyrie and Rudolf Ushiromiya who shot and killed everyone (except Eva, who killed back in self-defense) so they could get the Rokkenjima treasure.
* ''VisualNovel/PhoenixWrightAceAttorneyTrialsAndTribulations'' has between one and four antagonists for the final case of the original trilogy depending on how you count.
* In ''VisualNovel/AceAttorneyInvestigationsMilesEdgeworth'', a contradiction arises from initially missing this in case one.

[[folder:Films]]

* ''ComicBook/NickFuryAgentOfShield1968'': The first issue opens with a variant of this. Fury breaks into a building but is shot dead by a masked man who catches him by surprise. It's then revealed that 'Fury' was actually an 'Life Model Decoy' android duplicate, and the masked man was the real Nick Fury - it was all a FakeActionPrologue, a training exercise to test the android's abilities. But ''then'' it's revealed that the L.M.D. was shot ''four'' times, and Fury only fired three - the villain of the story, Scorpio, has stealthily interrupted the training exercise with a simultaneous AssassinationAttempt, assuming that he was shooting the real Fury.