Counterproving

from The Collaborative International Dictionary of English v.0.48

Counterprove \Coun`ter*prove"\ (koun`t?r-pr??v"), v. t. [imp. &
   p. p. {Counterproved} (-pr??vd"); p. pr. & vb. n.
   {Counterproving}.]
   To take a counter proof of, or a copy in reverse, by taking
   an impression directly from the face of an original. See
   {Counter proof}, under {Counter}.
   [1913 Webster]