use Digest::MD5;
use strict;

%seen = ();
$dirname = "/path/to/files";

# Parse over files in directory
opendir(DIR, $dirname) or die "can't open $dirname: $!";

# Take a careful look at each file in $dirname
while (defined($file = readdir(DIR))) {
    my $file = "$dirname/$file";
    open(FILE, $file) or die "Can't open '$file': $!";
    binmode(FILE);

    # make a $hash of each file
    my $hash = Digest::MD5->new->addfile(*FILE)->hexdigest, " $file\n";

    # store a copy of this $hash and compare it with all others seen
    unless ($seen{$hash}++ {
        # this is a unique file
        # do something with it here - perhaps move it to a /unique location
    }
}
closedir(DIR);