Farscape/Recap/S03/E06 Eat Me

Season 3, Episode 6:

Eat Me
Moya encounters a sick, Peacekeeper-controlled Leviathan that houses criminally insane prisoners, and a villain capable of "twinning" people in order to use them as food. The crew manage to escape the Leviathan in time, but thanks to the twinning, Moya now has two completely identical John Crichtons aboard.