The Collaborative International Dictionary of English v.0.48:

Duplicate \Du"pli*cate\, v. t. [imp. & p. p. Duplicated; p.
   pr. & vb. n. Duplicating.]
   1. To double; to fold; to render double.
      [1913 Webster]

   2. To make a duplicate of (something); to make a copy or
      transcript of. --Glanvill.
      [1913 Webster]

   3. (Biol.) To divide into two by natural growth or
      spontaneous action; as, infusoria duplicate themselves.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "duplicated":
   biform, bifurcated, bilateral, bipartisan, bipartite, dichotomous,
   double, doubled, duadic, dual, dualistic, duplex, dyadic, echoed,
   identical, matched, plagiarized, quoted, rechauffe, redoubled,
   reduplicated, reechoed, regurgitated, reiterate, reiterated,
   repeated, reproduced, retold, twain, twice-told, twin, twinned,
   two, two-sided, warmed up