资料来源 : Webster's Revised Unabridged Dictionary (1913)

Identicalness \I*den"tic*al*ness\, n.
   The quality or state of being identical; sameness.

资料来源 : WordNet®

identicalness
     n : exact sameness; "they shared an identity of interests" [syn:
          {identity}, {indistinguishability}]