Teenage Mutant Ninja Turtles (1987): Season 5, Episode 12 - ProjectFreeTV

5 - 12: Donatello's Duplicate

Tired of fixing everything in the lair, Donatello decides to clone himself so he can work on his other inventions. However, Donatello's clone turns against him and joins the Rat King in an attempt to conquer the city with a rat infestation.