#!/usr/bin/env perl -l

use strict;
use warnings;

my @test_strings = qw{
    abcdefghiaabccdjklm
    abcdeffghijkllmnoppqestqaserb
}; 

remove_duplicate_chars($_) for @test_strings;

sub remove_duplicate_chars {
    my $str = shift;

    my %seen;
    my @chars = grep { ! $seen{$_}++ } split //, $str;
    my $uniq = join '', grep { $seen{$_} == 1 } @chars;

    print "IN:  $str";
    print "OUT: $uniq";

    return;
}

##</code><code>##

IN:  abcdefghiaabccdjklm
OUT: efghijklm
IN:  abcdeffghijkllmnoppqestqaserb
OUT: cdghijkmnotr