3rd Rock from the Sun

See Dick Run (1x20)

Air date: May 21, 1996

Dick cuts up at a Japanese restaurant, but the big news is that he's there with Dr. Albright, who has finally agreed to date him. But just as they finally consummate their attraction, Harry receives bad news from the home planet: Dick has been replaced by a less benign duplicate, who traps him in the basement and takes charge of Dr. Albright.