#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my @pchr = qw( K Q R B N P );
my $w1   = 'QRKPNBQ';  # <- Q is repeated!
my $w2 = join "", map $_ x (() = $w1 =~ /$_/g), @pchr;
say "$w1 \-> $w2";