Since Duplex is a comedy set in Brooklyn's cutthroat housing market and is about a sweet-faced little old tenant from hell who torments her yuppie landlords into plotting to kill her, it's time to haul out the homeowner metaphors: The building materials are top quality -- Ben Stiller and Drew Barrymore star, Danny DeVito directs, the script is by Larry Doyle (''Beavis and Butt-head'') and John Hamburg (''Meet the Parents'') -- but the workmanship is shoddy. You know the roof leaks when Barrymore vomits on Stiller's face in a joke involving plumbing repair. You know the architects started out with higher hopes when Wallace Shawn, Swoosie Kurtz, and Harvey Fierstein make cameo appearances. (Eileen Essell plays the unbudgeable old lady.)
What looks good in the blueprint -- both DeVito and Stiller specialize in the ways of ruthless people -- runs into construction problems, maybe from too many foremen. DeVito favors pushy slapstick; Stiller prefers hotshot sarcasm. Barrymore's comic talents are wasted; she's there for decoration.