What is another word for "duplex"?

Roget's Thesaurus (1911) lists these synonyms for "duplex": and, biformity, binary, binate, binomial, biparous, biplicity, both, brace, bracket, conduplicate, conjugate, conjugation, couple, deuce, double, doublets, dual, dualism, dualistic, duality, duet, duplicity, dyad, dyadic, gemini, mate, one, other, pair, polarity, span, tete-a-tete, the, twin, two, unijugate, unite, yoke.