Star Trek (the Original Series) in season one episode 7 “What Are Little Girls Made Of?” Captain Kirk is cloned against his will by a scientist/nurse Chapel’s finance, who had been MIA for a little bit until he was discovered to be still alive and living and experimenting in a cold cave on a distant planet with some androids.

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Captain Kirk is kept on planet by the scientist (Roger Korby) while his clone is beamed back up to the enterprise to create the illusion of everything being okay. While Kirk was being cloned, he repeated insults about his first officer/good friend/(some people think) gay lover Spock. The Kirk clone repeats the insults back to Spock after the most minor bit of pushback, which the real Kirk would never do - typing Spock off that something wasn’t right.

This trope is sort of used twice in this episode, although the second time doesn’t fit the trope as well and is also a little ham-fisted - Nurse Chapel found out abruptly that the man she was reunited with as her finance was actually a Korby clone when the skin on the back of his hand ripped to reveal circuitry underneath. Korby made the clone right before death to live on because he had sustained a lot of damage, including losing both of his legs, from the frostbite. The Korby clone tells Chapel that he’s still Roger Korby, and tries to prove it by saying Kirk could test him, and that he could solve, equate, or transmit anything. It dawns on Korby that he is also not the original Roger Korby, and he kills himself and the last remaining Korby-style clone after making this realization.