Source : Webster's Revised Unabridged Dictionary (1913)

Mackle \Mac`kle\, n. [See {Macle}.]
   Same {Macule}.

Mackle \Mac"kle\, v. t. & i.
   To blur, or be blurred, in printing, as if there were a
   double impression.

Source : WordNet®

mackle
     n : a printed impression that is blurred or doubled