The Collaborative International Dictionary of English v.0.48:
Identicalness \I*den"tic*al*ness\, n. The quality or state of being identical; sameness. [1913 Webster]WordNet (r) 3.0 (2006):
identicalness n 1: exact sameness; "they shared an identity of interests" [syn: identity, identicalness, indistinguishability]