What's New, Scooby-Doo? (2002)

S03E03 A Scooby-Doo Valentine

The gang finds themselves in a bizarre situation as local teens are being abducted by impostors resembling them. Amidst the chaos, Shaggy learns that his former girlfriend is now in a relationship with J.C. Chasez. As they unravel the mystery, the group must confront their lookalikes to save their friends and get to the bottom of this strange occurrence.