The first thing to do with complex data structures is to print them out with use Data::Dumper; print Dumper $mysteriousStructure;

The symptom of getting the same thing on two branches is often a problem of storing multiple references to the same old array or hash.

my @array;
my %hash;

push @array, 'foo';
$hash{ref1} = \@array;
push @array, 'bar';
$hash{ref2} = \@array;
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At that point, both entries in the hash point to the same array, and that array contains both 'foo' and 'bar'.