Duplicates an object or person
Justin is the first wizard shown to attempt the spell. He executes it almost perfectly, except the duplicate rabbit barks. He admits he was thinking of dogs when he executed the spell.
Alex later uses the spell to duplicate herself. However, since she was thinking of Justin's barking rabbit, her spell doesn't work out well.
Alex uses the spell again when Jerry asks her to duplicate him so he can go dancing with Theresa, and watch the big game that was coming on. This time the spell appears to have worked well, and the duplicate Jerry walks off to take Theresas dancing.