Synonyms and related words :
Janus-like, ambidextrous, bifacial, bifold, biform, bilateral, binary, binate, biparous, bivalent, conduplicate, copy, disomatous, ditto, double, double-faced, dual, dupe, duple, duplex, duplicate, geminated, ingeminate, multiply by two, redouble, reduplicate, repeat, replicate, reproduce, second, secondary, twin, twinned, two-faced, two-level, two-ply, two-sided, two-story, twofold