The Collaborative International Dictionary of English v.0.48:

Quadruplicate \Quad*ru"pli*cate\, v. t. [imp. & p. p.
   Quadruplicated; p. pr. & vb. n. Quadruplicating.] [L.
   quadruplicatus, p. p. of quadruplicare, fr. quadruple?
   fourfold. See Quadruplex.]
   To make fourfold; to double twice; to quadruple.
   [1913 Webster]