That seems like an overly complex version of:

use File::Find;
use Digest::MD5 qw(md5_hex);

my %same_sized;
find sub {
  return unless -f and my $size = -s _;
  push @{$same_sized{$size}}, $File::Find::name;
}, @ARGV;

for (values %same_sized) {
  next unless (@ARGV = @$_) > 1;
  local $/;
  my %md5;
  while (<>) {
    push @{$md5{md5_hex($_)}}, $ARGV;
  }
  for (values %md5) {
    next unless (my @same = @$_) > 1;
    print join(" ", sort @same), "\n";
  }
}
[download]

Or am I missing something?

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.