The Emperor's New School (2006)

S1E13 Kuzclone

The class is assigned to write about their best friends, but Kuzco struggles since he has no true friends. In a pinch, he invents a fictional buddy. When he’s asked to introduce this friend, to his surprise, a doppelgänger appears! Unbeknownst to Kuzco, this lookalike is actually a clone created by Yzma.