Teenage Mutant Ninja Turtles (1987)

S5E12 Donatello's Duplicate

Title: Donatello's Double Plot: Eager to dedicate more time to his inventions, Donatello hatches a plan to clone himself, allowing his replica to handle chores around the Lair. During a trial of his newest device on a sewer rat, an unexpected mishap occurs when Donny's hand interferes, resulting in the rat clone mimicking his voice perfectly.