Interesting method. The bad news is that it can only be used once (try princepawn's test case, setting @d = qw/a a a a a a a/). But the good news is that it can be reduced to 18 :)

sub all_eq {
  (@_{@_}=1)==keys%_
}
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update: 17 chars...

  @_{@_}=0;keys%_<2
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   MeowChow                                   
               s aamecha.s a..a\u$&owag.print