Janus, ambiguity, ambivalence, biformity, bifurcation, bush, bushing, conduplication, conjugation, copying, crease, creasing, crimp, dichotomy, dog-ear, double, doubleness, doublethink, doublure, dualism, duality, duplexity, duplicate, duplication, duplicature, duplicity, echo, equivocality, facing, filler, filling, flection, flexure, flounce, fold, frill, gather, gemination, halving, imitation, ingemination, inlay, inlayer, insole, interlineation, irony, iteration, lapel, lappet, liner, lining, packing, padding, pairing, plagiarism, plica, plication, plicature, ply, polarity, quotation, reappearance, rebirth, recurrence, redoubling, reduplication, reecho, regurgitation, reincarnation, reiteration, renewal, reoccurrence, repetition, replication, reproduction, resumption, return, ruche, ruching, ruffle, stuffing, tuck, twinning, two-facedness, twoness, wadding, wainscot