use strict;

open( CDR, $CDR ) || die "Can't read $CDR\n";
open( DUP, ">$CDR.dup" ) || die "Can't write $CDR.dup\n";
open( UNQ, ">$CDR.unq" ) || die "Can't write $CDR.unq\n";
my %seen;

while (<CDR>) {
    if ( exists( $seen{$_} )) {
        print DUP;
    }
    else {
        $seen{$_}++;
        print UNQ;
    }
}