Dupe is the twenty-sixth episode of Season 1 of Lilo & Stitch: The Series. It aired on December 29, 2003.
Plot
Lilo hosts a slumber party, but none of her classmates from hula school come. When she finds an experiment that multiplies individuals, she tries to multiply herself so that she can have friends. Stitch saves her, but is multiplied. Stitch is weakened by the multiplication when his strength is divided among all the duplicates. Gantu is able to use several experiments to capture Stitch. Lilo tricks Gantu into using Dupe to turn his few experiments into an army and then combines the Stitches back into one full-strength Stitch.