I'll expound on merlyn's comments.

To use your data structures, you can do this:

#create list of hashes
my @allhashes = ( \%hash1, \%hash2, \%hash3 );

#note the following assumes all keys exist and are the same
#keys are not sorted in this example
foreach my $key (keys %hash1) {
    print "key $key\n";
    foreach my $hash (@allhashes) {
        print "Value: $hash->{$key}\n";
    }
}
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The better way to do it, as merlyn said, is to create your nested data structure from the top. Rather than creating (N) different hashes with the same keys, create a list of hash references (just like @allhashes above), and populate that with whatever method you are populating your hashes with now.

Re-Update: Deleted a bunch of stuff that I thought was relevant, but wasn't.