Over its 10-season run, Friends had many running gags, however, it may have accidentally repeated a joke about Joey having an identical twin without even realizing it. At the end of Season 5, episode 24, “The One in Vegas: Part 2,” Joey desperately tries to convince a blackjack dealer to go into business with him after noticing that the two of them have the exact same hands. Joey refers to this phenomenon as having found his “identical hand twin.”

Given how long the show went on for, it was somewhat inevitable that continuity and repetition would be an issue: stories often returned to the same well for inspiration, while inconsistencies like Rachel saying she needed glasses and then never wearing them propped up a surprising amount. But outright repeating a joke is a little less forgivable. And not too many episodes after the initial twin gag, Friends accidentally repeated this joke. In the very next season, episode 17 “The One With Unagi,” Joey is turned down by a medical study for not being an identical twin. Later, Joey (ever the struggling actor) bumps into another aspiring actor at an audition, and feels he looks like his identical twin, and tries to convince him to do the study together so they can earn some cash.

However, in both episodes, the same joke is repeated almost exactly: Joey tries to convince a “twin” of his to scheme together for money, while everyone around him remarks that the two of them actually look nothing alike. In Vegas, Joey’s “hand twin” often remarks that not only are their hands hardly similar, but that the idea of having a “hand twin” makes no sense to begin with. Furthermore, when Joey introduces Monica and Chandler to his other “identical twin,” in season 6, both of them comment on the fact that the actor looks nothing like him.

As an example, in Vegas, Joey and Phoebe both work together to try to convince Joey’s “hand twin” (played by Thomas Lennon) to cooperate in the scheme. Ross, on the other hand, tried unsuccessfully to explain to Joey that there’s no such thing as an “identical hand twin.” Undeterred, Joey continues to berate his “hand twin” until it eventually gets him kicked out of the casino. In this joke, Joey never learns his lesson nor understands why his “hand twin” doesn’t want in on the deal.

In almost exactly the same way, only one season later, Joey tries to convince fellow actor Carl to go in on a medical twin study. Sure that his plan will work, he teaches Carl how to act like him, despite the fact that they look nothing alike, and tests his plan in front of Monica and Chandler, sending Carl (who almost played Joey himself) into the apartment to greet them as if he was Joey. Of course, Monica and Chandler see right through this, and question the integrity of Joey’s plan. When the time comes for the study, the researcher involved immediately rejects Joey and Carl saying plainly that they can’t participate because they’re obviously not identical twins. Joey, of course, blames Carl. This joke plays out in almost exactly the same way as it does with Joey’s “identical hand twin,” where Joey never learns why his plan doesn’t work.

Though a sitcom often relies on the concept of “running gags,” or repeated bits that carry over season to season, these two jokes from the long-running sitcom feel more staled and repeated than your average runner. Friends, in particular, was known for funnier, more clever running jokes such as Phoebe’s song “Smelly Cat.” However, Joey’s running gag regarding “identical twins” on Friends may have just run out of steam early, or just been clumsily repeated.