sorry for my ignorance Anonymous, but what are you demonstrating here? can you explain your code?

Um, what do you think I'm demonstrating? What do you understand about the code?

:)

I think I'm demonstrating that reference adresses get reused rather quickly ...

Is this relevant for the OP? I can't say :|

If all that happens is  my %f = ([],[]); my %g = reverse %f; then both %f and %g will have unique key-value pairs guaranteed

If at some point other references are added as keys then collisions will happen