lanx@nc10-ubuntu:~$ perl -e '@k=( %h=(a=>42,b=>2,a=>1) ); print "$] Bug: @k\n" unless @k ~~ [%h]'
5.010000 Bug: b 2 b 2

##</code><code>##

lanx@nc10-ubuntu:~$ perl -e '%h2=@k=( %h=(a=>42,b=>2,a=>1) ); delete @h{keys %h2}; print "$] Bug: @k\n" if %h'
5.010000 Bug: b 2 b 2