For sure the sorts don't mess around with your hashes, they merely peek into it and produce a sorted list of keys.

However the sub check_around is probably not doing what you intended it to do. It will always return the same value as what $doc brings. The variable @doc_block is not declared and therefore its values are undef.
Update:$doc_block[1] is always undef (you shift the array if the number of elements>1 elsewhere in your code).

sub check_around{
    #my $self = shift;
    my ($doc,$switcher) = @_;


    if ($doc_block[0] eq $doc || $doc_block[1] eq $doc){
       return undef;
    }
    else {
       return $doc;
    }
}
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NB: use warnings would have signalled the issue and it would have saved you time.