Just out of curiosity are you trying to do something like this

#!/usr/bin/perl

use warnings;
use strict;

my @files = get_files();
my %single_hash;

for my $file (@files){
  open my $fh, q{<}, $file
    or die qq{open to read $file failed: $!\n};
  my $file_as_string = do{local $/;<$fh>};
  push @{$single_hash{$file_as_string}}, $file;
}

for my $value (values %single_hash){
  print qq{@{$value}\n};
}


sub get_files{
  # stuff
  return qw{one two three};
}
[download]

files one and two

one
two
three
four
[download]

file three

one
two
three
four
five
[download]

output

three
one two
[download]

Two files (one and two) are the same i.e. not unique. Am I warm?