Actually in the bigger picture im arguing for exactly such a distinction. I beleive Test::More should supply a "looks_like()" function which wouldn't give a toss about reference counts and that the subroutine called is_deeply() should do what its name suggests and do a deep structural comparison (ie care about reference counts). Especially as I know that the code base currently handling is_deeply() can be relatively trivially be extended to support both behaviours.