Off the top of my head, if you're not worried about exactly which bytes differ, I would take the MD5 digests of the files and see if these differ. Something like the following will work:

#! /usr/bin/perl -w

use strict;
use Digest::MD5;

my $orig = shift or die "no original given\n";
my $dup  = shift or die "no copy given\n";

open ORIG, $orig || die "Cannot open $orig for input: $!\n";
my $origmd5 = Digest::MD5->new;
my $origdig = $origmd5->addfile( *ORIG )->digest;
close ORIG;

open DUP, $dup || die "Cannot open $dup for input: $!\n";
my $dupmd5 = Digest::MD5->new;
my $dupdig = $dupmd5->addfile( *DUP )->digest;

print( $origdig ne $dupdig ? 'not ' : '', "ok\n" );
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