The Collaborative International Dictionary of English v.0.48:

Dupe \Dupe\, v. t. [imp. & p. p. Duped (d[=u]pt); p. pr. & vb.
   n. Duping.] [Cf. F. duper, fr. dupe. See Dupe, n.]
   To deceive; to trick; to mislead by imposing on one's
   credulity; to gull; as, dupe one by flattery.
   [1913 Webster]

         Ne'er have I duped him with base counterfeits. --
                                                  Coleridge.
   [1913 Webster]