use strict;
use warnings;

my ($RB1, $RB2, $WR1, $WR2, $TE1) = (1, 2, 3, 1, 4);
{
my %lookup;
for ($RB1, $RB2, $WR1, $WR2, $TE1) {
    if ($lookup{$_}++) {
        print "Dupe $_\n";
        last;
    }
}}