Duplex, meaning double or twofold, commonly refers to: Duplex (building), a two-unit apartment building or condominium Duplex (telecommunications), a telecommunications system where signal can flow in both directions between connected parties; half-duplex flows in one direction at a time, full-duplex flows in both directions at the same time Duplex can also refer to: Arts and music Duplex (film), a 2003 movie starring Ben Stiller and Drew Barrymore Duplex (band), a Dutch electronic music… (More on Duplex)