Dresses the Same

Thus began the most well-dressed Cat Fight ever.

A woman buys a dress to wear to some event, and is humiliated when she sees another woman wearing an identical dress.

Truth in Television, at least for some women. It doesn't matter if she bought her dress at the snooty boutique or the local Walmart (though if it is from Walmart, then both suffer the humiliation of knowing that another woman knows she got her dress from the bargain bin), wearing the same dress is undeniable proof that she's bought a mass-produced consumer item, breaking any illusion of the dance taking place in a Jane Austen novel where all the dresses have to be hand-made. Reportedly, the painstaking process of selecting a dress makes her identify it so strongly as 'hers' that to see another woman in the same dress is akin to seeing another woman with her boyfriend.

Contrast Whole Costume Reference (in that wearing the same outfit is considered a good thing).

Examples of Dresses the Same include:

Anime and Manga

During the class trip in Azumanga Daioh, Kaorin shows up at one point in a souvenir T-shirt... only to see Mr. Kimura wearing it, at which point she runs off to go change. Though this was more because he's an admitted Ephebophile than for social reasons.

Comic Books

Classic John Callahan comic panel: A woman at a funeral is leaning over the coffin and thinking, "That BITCH!" The deceased is wearing an identical dress.
Often happens to Veronica in Archie Comics.
- In one story, Betty and Veronica appear at a party in the same dress, and they both act as if it must be a dream, because the thought of them wearing identical dresses is so outrageous, so terrible, that they refuse to believe it can be true. When they finally realize that it isn't a dream, not only do they destroy each other's dresses, but they wreck the entire place. Can you say Serious Business?
- In another story, Veronica asks Betty to make her a one-of-a-kind swimsuit, even asking if she's made any other girl a swimsuit out of a particular bolt of fabric. Turns out Betty used that fabric to make swimsuits for a bunch of guys.
Katy Keene has done this with Katy and Gloria.
- In the picture above, they have the same "Happy Holidays" Dress, fur muff, and even dress pose.

Film

Parodied in Not Another Teen Movie, where two girls separately appear at a party naked.
Happens in the Lindsay Lohan version of Freaky Friday; Lindsey and another girl wear the same shirt to school. Lindsey turns her shirt inside-out to avoid looking the same and looks...well, actually, stupider than if she had just left the shirt as it was.
In My Fair Lady at Ascot, there are two women with the same outfit (including hats). Cue frosty looks and consequent ignoring of each other.
Daphne avoids this in Unfaithfully Yours by asking her sister what fur she will be wearing so that she wouldn't wear the same one.

Live Action TV

There's an I Love Lucy episode about this happening to Lucy and Ethel. It climaxes with them tearing decorations off each other's (highly) overdone dresses.
There's a Sister, Sister episode about their senior prom. The girls had bought a dress they liked each but Lisa had made them some too, in order to not hurt her feelings the girls planned to change in the back of the Limousine. When they did, and went to the prom, all the girls there were wearing either Tia's dress or Tamera's dress. They go back to the Limo but they're locked out, when Ray and Lisa show up Lisa's miffed initially but in the end it all works out.
Lizzie McGuire: Kate and Miranda wear the same outfit on Picture Day.
Monk: Randy shows up to a Christmas party with a sweater his aunt supposedly made for him by hand... except there's another guy at the party in the same sweater, and he got his at Wal-Mart.
Used in the Wings episode "The Waxman Cometh." When Casey goes to the grand opening of Lowell's new wax museum, she is mortified to see that the museum's wax figure of Eva Gabor is not only wearing the same dress as her, but also has better jewelry.
A variation appears in the Mama's Family episode "There's No Place Like...No Place." When Thelma is mistaken for being a vagrant and arrested, she asks the cop, "Do I look like a homeless person?" Just then, an actual bum is brought in behind Thelma, wearing the same housedress as her. The newcomer comments, "Cute dress. You get yours at the mission too?"
An episode of the 90s sitcom Living Single features the ladies going out to the club. Regine sees other women wearing her dress, and proceeds to go up to them and "accidentally" spill her drink on them so they'll leave to go change.
On The Golden Girls, Dorothy and Blanche buy the same dress for an occasion. Each takes her dress back without telling the other, trying to be the nice one. After a brief scare that they've bought the same dress again, they reveal two totally different dresses, only to have Sophia emerge wearing the same dress as Blanche.
- In another episode, when Rose and Sophia are competing against Dorothy and Blanche in a bowling tournament, Rose and Sophia invoke this trope by buying the same bowling shirt as Blanche, in order to throw her off her game.
In the Thirty Rock episode "Goodbye, My Friend," Jenna gives Kenneth a picture of her dress for her birthday party, telling him to make sure that no one else wears it...Only to have Cerie show up wearing it.
In a Halloween episode of The Big Bang Theory, the nerds initially show up all dressed as The Flash. Sheldon comments "See? This is why I wanted to have a costume meeting."
- Judging by their disappointed reactions to Leonard "calling" Frodo, it might have happened a second time.
In the Buffy episode Angel, Cordelia spots a girl wearing a dress identical to her own, and accuses her of wearing a cheap knockoff of her designer original. "This is exactly what happens when you sign these free trade agreements!"
- And in the Angel spin-off, Cordelia complains when she sees a woman at a homeless shelter wearing her one-of-a-kind blouse—unaware that Angel gave away her blouse to the shelter.
- In "Couplet" Angel thinks that Groo is taking over his life. Wesley assures him they are two completely different people—only to bump into Groo with Angel's Spiky Hair and Badass Longcoat.
- Angel should know better than to make light of this trope: in the Buffy episode Lie to Me he bitches about Vampire Vannabes thinking they know how vamps think, act and dress. Cue one of the said vannabes walking by dressed exactly as Angel.
In the Look Around You episode "Maths", one of the problems is to compute the probability that Queen Elizabeth III, Queen Elizabeth IV, and Queen Elizabeth V all show up at a party wearing the same dress. The answer: the party is canceled.
In an opening of The Amanda Show, Amanda and Nancy Sullivan were embarrassed to find out they were wearing the same dress to the show, as were Drake, Josh, the Camera men and the Dancing Lobsters.
During The Tag at the end of an episode of Community. Abed and Troy both spoke in unison with and dressed the same as Jeff. Annie apparently wanted in on the gag too, but got stuck in traffic and arrived just after the joke had ended.
In the second All Star edition of The Amazing Race (Unfinished Business), this was deliberately invoked as a joke by Zev & Justin, when they showed up to the starting line wearing the same Globetrotter gear worn by Harlem Globetrotters Flight Time & Big Easy when they originally raced together on a previous season.

Music

The trope appears in the music video for the Reel Big Fish song "She Has a Girlfriend Now," in which the identically-bedressed girls get into a knock-down-drag-out chick fight.

Newspaper Comics

Parodied in a The Far Side cartoon, where a cowboy wearing a flowery, decorated hat balks at entering a saloon where another cowboy is wearing an identical hat. All the other cowboys, of course, are wearing the usual style of cowboy hat, all alike.
- Another has two chameleons in the same color at a party.
- Yet another is a psychic convention, where they not only wear the same dress but the exact same hair and makeup. The punchline is that it was completely unforeseen.
Variation in this Dilbert comic.
Subverted in a Pondus strip where Pondus' wife demands that they leave the party because someone else is wearing the same dress as her. Pondus tries to convince her that it's no big deal, until he sees that the person wearing the same dress is a transvestite. Then he cries out for a taxi.
In one early Tank McNamara strip, tennis player Barb was going to play Chris Evert, and wanted an edge. Her boyfriend suggested she wear a tennis dress identical to Chris's. Barb said angrily that "even in jest that's an asinine, sexist, stupid, dumb, male idea ... and it really disgusts me that I'm going to try it." The last panel of the next strip showed Evert missing a shot while wondering frantically, "Where'd she get it? Where'd she get it?"
In a series of FoxTrot comics, Andy forces Peter to wear a dorky shirt on the first day of school: "I'm asking you to dress nicely for one day. How bad can that be?" When he gets to school, he discovers, to his horror, that super geek Morton Goldthwait is wearing the same shirt. Hilarity Ensues.

Theater

"Paris Original" from the musical How to Succeed In Business Without Really Trying takes this to its logical extreme, as each secretary enters in succession, and reacts in horror as she sees every other one wearing the same dress: "Some irresponsible dress manufacturer just didn't play fair!"

Web Comics

Tedd and Elliot both showing up in girl's school uniform for that weird birthday party in El Goonish Shive. Tedd invokes it for his (her?) own reasons; Elliot calls it as he (she?) sees it.
Parodied in this Sluggy Freelance strip where Zoe dresses as a sexy French maid for a Halloween party, forcing Torg to change out of his sexy French maid costume.
Happens in CRFH. It ends badly.
Parodied in Rhapsodies here where this makes a run in with a high ranking society lady, Kate had accidentally insulted in the past, worse.
Happened between Ki and Trudy at a party on General Protection Fault. Nick doesn't see what the fuss is, as all of the guys are wearing the same outfit. Then he realizes that he's talking to Fooker, who is the only person present whose tuxedo is plaid.
Cute variant in Girls with Slingshots, where Thea worries that her top is too old-fashioned; cue her girlfriend's mother in the same outfit.

Web Original

In one episode of RWBY Chibi, Team RWBY is attending a costume party where they've all dressed as each other -- Ruby as Weiss, in particular. Cue the arrival of an irate Jaune, also dressed as Weiss, growling, "One of us is going to have to change."

Western Animation

A gag in Family Guy had Peter and Lois were wearing the same dress, and Peter expected Lois to change.
- During a costume party, Stewie and Brian both come as Snoopy.
Happens once in Jimmy Two-Shoes, where Heloise actually gets Jimmy's attention by wearing a fancy dress at a premier.

Jimmy: Oh, Heloise, nice outfit.
Heloise: (Coy) It's an original. (Sees a girl wearing the same thing and tears it to shreds)

In Phineas and Ferb episode "De Plane! De Plane!", Candace finds a girl who wears the same swimsuit as her, only hotter.
Parodied in Beverly Hills Teens, where Bianca and Larke wore the same outfit to a costume party (save for some color differences), and then both got changed into new outfits, that are still the same.
In the Ed, Edd 'n' Eddy Picture Day episode:

Johnny: (holding out Plank) Hey, Jimmy! You and Plank ordered clothes from the same catalog! (Jimmy is horrified)

Done in an episode of Kappa Mikey. Lilly and Mitsuki see each other and gasp... Then pan out to Mikey, Gonard, and Guano, all three also wearing the same dress.

Jokes

This Star Trek: The Next Generation photo caption.
Those tongue-in-cheek internet lists on "Why it's Great to be a Guy" usually include this subversive chestnut: If another guy shows up at a party wearing the same outfit as you, the two of you just might become best friends for life.