In The Charge at Feather River, Smiley and Cullen (the drunkard and the thief) are almost always seen together and provide most of the Comic Relief: most often through Cullen's attempts to filch Smiley's stash of booze.
The Death of Stalin: The two unfortunate soldiers on duty outside of Stalin's office when he dies, and who are left standing there most of the day without an order to 'stand down':
Guard 1: [hearing Stalin's body hit the floor with a thud] Should we investigate...? Guard 2: Should you shut the fuck up before you get us both killed?
Jenny's friends Hattie and Tina in An Education. They hang on every detail of her unfolding love story, but either they dump her or she dumps them about midway through the plot, and they're never seen again.
Mariah Carey's woeful "star vehicle" Glitter has Louise and Roxanne.
Gregory's Girl: Andy and Charlie, who spend most of the film trying to get girls.
Razor and Blade, hosts of "Hack the Planet" from Hackers.
Harold & Kumar Go to White Castle and its sequels have the two Jewish guys, Rosenberg and Goldstein, direct Expys of the titular characters from Rosencratz and Guildenstern Are Dead.
Tahei and Matashichi from Akira Kurosawa's The Hidden Fortress. R2-D2 and C-3PO are loosely based on them.
Hot Fuzz has "The Andies", Andy Cartwright and Andy Wainwright.
Hannah Montana: The Movie has Rico and Oliver as two regular school guys helping out at Lily's party and not having any importance to the plot. In the TV series, it's the complete opposite as Oliver in particular is the male lead of sorts and often has a major/central role (that is until he leaves in season 4).
Specs and Tucker in Insidious and its three sequels. They provide much of the comic relief while also contributing to the plot, and end up becoming main characters in the later films.
From It's a Mad, Mad, Mad, Mad World; Dingy Bell and Benjy Benjamin. Also, the two gas station attendants, Ray and Irwin. As well as the two cabbies at the end.
Kafka has the two childishly stupid assistants, two twin brothers who keep fighting constantly and are cause of some of the best comically kafkaesque scenes of the film, like when they try to open the writing desk in Kafkas office or play around with the typewriters. It is later revealed that they have been Evil All Along.
Marty and Todd in Kick-Ass (the first one only, as Marty has a more central role in the second film).
Killer Party has the fat and skinny frat boys from Beta Tau who toss the jar of bees into the sorority's backyard, and who later wear bee costumes to the hazing party. They are only identifies in the credits as 'Fat Bee-Boy' and 'Skinny Bee-Boy'.
The block print seller and the carpenter in Lady Ninja Kaede who comment upon the news of the rapes, suicides, murders, ninja attacks, and executions as it has filtered down to the common folks.
A very early film example are Charters and Caldicott from The Lady Vanishes (and later Night Train to Munich, and a half-dozen other movies of the early '40s) who spend their on screen time mostly obsessed with the current cricket scores. They have their very own adventure in Charters and Caldicott by Stella Bingham. The pair are still obsessed by cricket and go from lunch at their club to Caldicott's flat to settle a point in dispute with his 'Wisden' a Cricket reference work. They discover the body of a young woman on Caldicott's bedroom floor. Her purse identifies her as the daughter of an old friend. But then another young woman appears claiming to be the * real* daughter and that her father has been murdered - then it starts getting complicated.
In The Life and Death of Peter Sellers, Spike Milligan and Harry Secombe (Peter Sellers' colleagues from The Goon Show) pop up in a largely non-speaking capacity several times after the opening scene of a show recording, symbolizing Peter's disconnect with his old friends and his first great success out of his ambition to become a film actor, and his eventual alienation of virtually everyone he was ever close to. (Peter was actually quite close to these two guys throughout his life, but it's the kind of movie that's not interested in the good times.)
Manos: The Hands of Fate has those two teenagers who are sitting in a car making out with each other. They have no relevance to the plot in any way. It also has a pair of policemen, whose presence at least makes sense, even if they are just as meaningless.
Gonzo and Rizzo the Rat developed this popular dynamic in many of the Muppet productions of the '90s (though it has faded away as of late). Introduced in The Muppet Christmas Carol (where they play the narrators) and continues into Muppet Treasure Island and Muppets from Space.
The Bobs from Office Space. John C. McGinley, who played Bob Slydell, would play a similar role in The Pentagon Wars.
Pirates of the Caribbean: The series has two sets of these. One set are pirates who explain the convoluted plot to each other (Pintel and Ragetti), and the other set are a duo of Laurel and Hardy-inspired redcoats who are always debating things (Murtogg and Mullroy). At the end of the third movie, Murtogg and Mullroy just show up on Barbossa's ship, joining in the victory celebration and shouting cliche pirate phrases. Pintel and Regetti look at them for a moment, shrug, and start shouting right along with them.
Ashley and Jessica in Pitch Perfect and particularly the sequel. When Beca admits she doesn't know which of them is which, they both shout, "I'm Jessica!"
James and Eddie from the BBC Pride film. They're basically Those Two Guys in charge of the pride, having scenes about talking together, sleeping, and eating.
Mia's maids in the second The Princess Diaries movie. One of the few funny bits in the movie is when Lilly lampshades this by calling them Rosencrantz and Guildenstern. And then Lenny and Squiggy.
Darryll and Omar in The Return of Swamp Thing, two kids who first are saved by Swamp Thing, and later search for him in hopes of getting a photo worth 10,000 dollars.
The two NASA recruiters, played by Jeff Goldblum and Harry Shearer in The Right Stuff. Also apparently Gagarin and Titov in the intelligence film from Russia, which is lampshaded by the first pair, who argue which is which. The former pair accidentally put on each other's coats (N.B. Jeff is ten inches taller than Harry), are apart only momentarily, and serve as the main comic relief in the first half before the movie becomes a more sober historical epic.
Robin Hood: Prince of Thieves has the two guys who first argue over which is left and which is right, then try to rob Marian and Sarah in the woods.
Mahalik and CJ from the Scary Movie series. Their appearances sharply contrast, they're close friends with one of the main characters, and can usually be found engaging in Seinfeldian Conversation about something that is or could possibly be (such as whether one can "wake up dead" or "turn up missing").
Deputies Anthony Perkins and Ross Hoss in Scream 4, who are concerned that cops don't always survive horror movies. Or, usually, one does and one doesn't (unless you're Bruce Willis). Both of them die.
Echo magazine reporters Max and Milton from S1m0ne.
Sky Bandits has Aldiss and Nicky, the two British officers whose bet with Barney and Luke unwittingly dumps them into the thick of the action. They keep turning up in the background of the subsequent action, such as refusing to confess to stealing the Gunbus or very deliberately not noticing barney and Luke stealing the planes from their base
"Barracks Clowns" Harry and Animal from Stalag 17, who serve as both the comic relief and a renewed sign of optimism and free spirit in the camp.
R2-D2 and C-3PO have been Those Two Droids for nearly 40 years, present for many turning points in the galaxy.
Later (non-canon) comics reveal that practically any pair of Stormtroopers, Imperial guards, Clone troopers, Sandtroopers, no-name jedi, etc., is likely to be Tag and Bink, a pair of screw-ups who fumble their way from the Jedi Academy to the Tantive IV to the Death Star (both times), etc. Literally, pretty much any time you see two anonymous stooges in the movies, that's them right there.
Val and Earl from Tremors manage to be this trope despite also being the unlikely heroes of the film.
The two hillbillies that are seen watching the practices and the games in The Waterboy.
The Tournament has Eddie and Rob, the two techs charged with keeping track of the players and monitoring their progress. They provide a running commentary and act as Greek Chorus on the action.
The two brownies (no, they are little people, not chocolate) Franjeen and Rool in Willow.
Gringo and Luca from A Train for Durango are two men who are always together, always argue with one another and are both foolish and gullible.
Towne and Marriner in Northwest Passage. Although they're seen together less as the film goes on, through a good deal of it they're often traveling together and watching each others' backs.
Tahei and Matashichi from The Hidden Fortress, unlike Towne and Marriner, are practically inseparable. Although they bicker, they also can't do without each other.
The Walking Hills: Bar owner Bibbs and his guitar player Josh are constantly together, and provide a lot of levity while everyone else is filled with anger and distrust.——
