Scooby-Doo and Scrappy-Doo (1979)

S3E14 Punk Rock Scooby

At a lively rock concert, an alien doppelgänger of Scrappy suddenly appears, intent on eliminating Shaggy and Scooby. He believes they’ve abducted Scrappy, whom he mistakenly thinks is one of his own kind. Chaos ensues as the duo tries to explain the mix-up while dodging the alien’s attacks.