Buffy the Vampire Slayer (1997)

S5E3 The Replacement

A demon conjures a duplicate of Xander, leading the genuine Xander into a frantic race to prove to his friends that he is the real deal. As the doppelgänger begins to blend in and manipulate the group, Xander faces the daunting task of revealing the truth before it's too late. With trust on the line, he must outsmart the imposter while grappling with his own insecurities. Will he manage to reclaim his identity and restore faith among his friends?