This is where a character, for some reason or another, pretends to be their own (nonexistent) identical twin. It could be for disguise, or to see how their friends really think of them. Success rates vary.

See also TwinSwitch, BackupTwin. Subtrope of InventedIndividual.

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!!Examples:
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[[folder:Anime & Manga]]
* [[PlayingWithATrope Played with]] in ''LiightNovel/HaruhiSuzumiya''. Kyon and Mikuru pretend that Mikuru is "Michiru" - because [[spoiler:the "real" Mikuru is still around [[TimeyWimeyBall (blame time travel)]] and "Michiru" needs to [[NeverTheSelvesShallMeet hide from herself]].]]
* Maruko wants to do this by moving a mole in ''Manga/ChibiMarukoChan''.
* Jelal does this in ''Manga/FairyTail''.
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[[folder:Comic Books]]
* In ''Comicbook/{{Daredevil}}'', Matt Murdock pretended to be his own non-existent twin brother Mike Murdock to trick Karen and Foggy into believing that "Mike" was Daredevil when they began to suspect Matt's double life. This was back in UsefulNotes/{{the Silver Age of comic|books}}s when even Daredevil wasn't a very realistic series.
* In ''Big Bang Comics'', Ultiman is a CaptainErsatz version of Superman. However, Ultiman has worked for the government since gaining powers, and his identity as astronaut Chris Kelly is widely known... which is why he took on another identity as Chris' twin brother Carl, who works with Ultiman's superior Gen. Black and Black's secretary Lori Lake.
** A later issue reveals that there ''was'' a real, now deceased, Carl Kelly. Ultiman kept his brother's death a secret and adopted his identity because he was tired of having no private life.
* In the ''Creator/ECComics'' story Split Personality (Vault of Horror #30) a man scams a pair of rich twins into each marrying him, telling them that he has a twin himself and that they need to manage holdings in another country such that one is always away. [[spoiler: When they eventually realize the truth, the twins split him in half with an axe so each can have him.]]
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[[folder:Film]]
* In ''Film/TheBlackbird'', Dan, who is a notorious thief and criminal mastermind, disguises himself as the Bishop, the kindly operator of a Christian charity mission in the slums of London's Limehouse district. It's actually not clear what use his Bishop disguise is other than giving him a way to hide when the heat is on, but in any case, absolutely everyone believes it, including Scotland Yard and his ex-wife.
* In the Swedish movie ''Hajen som visste för mycket'' (''Film/TheSharkWhoKnewTooMuch'') Joakim Plottner has spent his ''entire life'' pretending to be triplets, who hate each other and refuse to spend any time in each other's company, keeping up a gambit his mother began when he was born. Even his father doesn't know the truth.
* In ''Film/TheLadyEve'', Jean is supposedly Lady Eve's illegitimate half-sister.
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[[folder:Literature]]
* Creator/MercedesLackey's ''Born to Run'' has one mechanic doing this as a practical joke to get back at a pair of elf twin brothers, who he had thought were just one person. To top it off, his fake twin name is Skippy.
* Literature/HerculePoirot:
** Poirot creates an imaginary twin brother named "Achille" in ''The Big Four'' - a parody of [[Literature/SherlockHolmes Mycroft Holmes]], in fact.
** The trope is ''vital'' in the novel [[spoiler: ''Elephants Can Remember'']] and its live action adaptation as a part of ''Series/{{Poirot}}'': [[spoiler: In this case, however, the twin ''exists''... or at least used to exist. A lady named Dorothea/Dolly, who had been mentally unstable all her life ''and'' was even more shattered after an horrible time in a mental hospital, snaps on her twin sister Margaret/Molly and fatally pushes her off a cliff. As Molly lies dying in her husband Alistair's arms, she makes him swear that not only he won't press charges against Dolly, but he will say that Dolly died while in reality helping her to pull this, so she can rebuild what's left of his life. Alistair complies... but later ''he'' snaps, [[MurderSuicide takes Dolly to the same cliff, shoots her dead and then commits suicide]].]]
* In Creator/RaymondChandler's essay "The Simple Art of Murder", he gives several examples of excessively contrived puzzles from the British whodunnit tradition, including a novel in which a FakeTwinGambit is used by the murderer to effectively frame the victim for his own murder (by doing him in while he's being the twin, so that it looks like murdered his twin and then went on the run). The novel in question is [[spoiler:''The Red House Mystery'', by Creator/AAMilne.]]
* The ''Literature/FearStreet'' novel ''Double Date'' has a Casanova jock trying to seduce twin sisters. They warn him that their mentally unstable triplet is on the loose and going after him and he realizes she's attacking him. It eventually turns out the triplet never existed, the twins were teaching the jock a lesson on behalf of all the girls he used in the past who are in on the scheme.
* ''Literature/VorkosiganSaga'': Miles Vorkosigan used a variation on this to cover for his "Admiral Naismith" identity, by spreading a rumor that Naismith was his clone. Between that and [[spoiler: his real clone-brother Mark]], he managed to create the impression for a while that there were ''three'' of him running around.
* ''Literature/SweetValleyHigh'': The Sweet Valley Twins did a fake ''triplet'' gambit where they invented a third sister and took turns pretending to be her.
* Snakeweed from ''Literature/TheDivideSeries'' pretends to be his identical twin Snakeroot in the second book when trying to find lodging, because Snakeweed was the BigBad of the first book and is trying not to let anyone discover that he's still around.
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[[folder:Live-Action TV]]
* In ''Series/AlloAllo'', after Rene faked his own death, he came back pretending to be his own twin. This received frequent LampshadeHanging during the series.
* Jane from ''Series/{{Coupling}}'':
-->'''Jane:''' I once went on holiday and pretended to be twins. It was amazing fun. I invented this mad, glamorous sister and went around really annoying everybody. And d'you know, I could get away with anything when I was my crazy twin Jane.
-->'''Sally:''' But you're Jane.
-->'''Jane:''' Kinda stuck. It's a long story.
* The Janitor tries to do this in ''Series/{{Scrubs}}'' as a prank on JD. JD isn't fooled for a second, causing the Janitor to ramp things up with more and more ridiculously phony "evidence" that he has an identical twin. In a last act of desperation, he claims that his brother is waiting for him at the bottom of the elevator, and when the doors open to reveal nobody he admits, "OK, I don't know what I thought was going to happen." It was perhaps the only time the Janitor failed to get the better of JD.
* Happens in the ''Series/TalesFromTheCrypt'' story "Split Personality". A conman fools a pair of reclusive and wealthy identical twin sisters into falling for him and his invented twin brother so he can collect on their fortune. When he accidentally reveals the ruse via his own carelessness, the sisters are ''very'' upset and decide to ensure that each gets her fair share for once -- [[HalfTheManHeUsedToBe with the help of a chainsaw]].
* On ''Series/ThreesCompany'', Jack told Mr. Furly that he had a twin brother who lived in Texas named Austin. This leads to a hysterical scene later in the episode where he has to pretend to be both of them at the same time around Furly.
* Played with on ''Series/{{iCarly}}'': Sam spends an episode trying to convince Freddie that she has a twin sister (who Freddie ends up going on a date with), before finally admitting that it was a trick. [[spoiler: And then after Freddie leaves, Sam's sister comes up in the elevator.]]
* Barney, from ''Series/HowIMetYourMother'', has been mentioned using this trope when trying to trick women into sleeping with him again after having already seduced and abandoned them. The audience has never been shown him actually ''doing'' it, but at one point an ex' assaults him while calling him by his fake brother's name, "Blarney"
** The final stage of his "Lorenzo Von Matterhorn" play was to be faking Lorenzo's death and then seducing the woman again as his brother, Julio Von Matterhorn.
** He also pretends to be a CampGay hairdresser and when the women he befriends wish that he was straight, he notifies them that he has a straight twin brother that they could go out with.
** In one episode, Lily stymies Barney's effort to seduce the twin of a previous conquest by claiming to have gotten chlamydia from him, then re-entering as her own supposed twin to rebuke him a second time.
* On ''Series/GoodEats'', when Alton's EvilTwin B.A. appears, it's pretty obvious to the audience that B.A. is just Alton in a DarkerAndEdgier costume, so it's PlayedForLaughs.
* A variation in ''Series/{{Charmed}}'' - Paige uses magic to impersonate Glen's fiancee Jessica and goes to marry him in her place. When Leo shows up with the real Jessica, he tells the confused priest that they're twins.
** In a different episode, Prue gets a mind-reading power and believes her new boyfriend is a warlock conspiring against her. It turns out that his troubling thoughts were only due to the fact that it was really the boyfriend's twin, whom the boyfriend had sent in to meet her.
* ''Series/ArrestedDevelopment'':
** As a prank, Maeby poses as her fictional twin sister Surely (yes, it's not spelled "Shirley"). Surely is depicted as rather sick with [=BS=] and a charity is set up for a cure.
** In [[Recap/ArrestedDevelopmentS2E5SadSack "Sad Sack"]], George Sr. poses as his twin brother Oscar in order to learn if his wife Lucille was in fact in love with Oscar.
* ''Series/MissFishersMurderMysteries'': In "Death Defying Feats", an identical twin had murdered her sister years before. When this act seems to be on the verge of catching up with her, she poses as her sister and claims that the two of them had faked her death to allow her to escape an abusive husband.
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[[folder:Radio]]
* A notable subversion happens in ''Radio/AdventuresInOdyssey.'' In Edwin Blackgaard's first episode, his appearance in Odyssey was set up to look like this, but it turns out Regis IS his evil twin and Edwin had no idea Regis had been there first.
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[[folder:Video Games]]
* In ''VisualNovel/UtaNoPrincesama'', Tokiya does this when entering the Academy in order to [[spoiler: try to break away from his Hayato persona and debut as himself.]]
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[[folder:Visual Novels]]
* In ''VisualNovel/HigurashiWhenTheyCry'', Mion does this in the Cotton Drifting Arc, when she claims to be her twin sister, Shion, a twin who never made an appearance in the previous arc, and who Rena and Satoko, some of Mion's best friends, don't know anything about. [[spoiler:The aforementioned is what Keiichi and the audience are led to believe, until shortly before the Cotton Drifting Festival, Shion tricks him into buying a doll that Mion had wanted him to give her from the toy store ''where Mion was working.'' Seeing the two twins side-by-side shows Keiichi - and by extension the audience - that Mion really does have an identical twin sister named Shion]].
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[[folder:Web Original]]
* In ''Roleplay/{{Raishon}}'', Eli pretended to be his own twin on the night of the Halloween Event while Zyera was (unwillingly) dressed up as him.
* In the ''Roleplay/GlobalGuardiansPBEMUniverse'', Carlos "Los Hermanos" Verdecia is a superhero with the power to duplicate himself into thousands and thousands of copies. He's often used one of his "dupes", as he calls them, as a Fake Twin when the occasion calls for it. In one story, he turned himself into fake triplets so he could date three women at the same time.
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[[folder:Webcomics]]
* ''Webcomic/{{Starslip}}'' has Vanderbeam trying this. [[http://starslip.com/2006/07/21/starslip-number-306/ Poorly.]]
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[[folder:Western Animation]]
* Subverted in ''WesternAnimation/GravityFalls''. [[spoiler:Stan]] did this twice in [[spoiler:his]] life, while having a real twin. They both worked.
* Angelica does this on an episode of ''WesternAnimation/{{Rugrats}}''. She puts her hair in a bun and rolls her sleeves up, pretending to be her nicer sister Ballina. Didi of course isn't fooled but plays along anyway. The babies believe it and prefer Ballina, which greatly annoys Angelica.
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