#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

sub unique_ids {
    my ( $length, $ids_ref ) = @_;

    # first check if we need to do something
    my %u_ids;
    %u_ids = map { my $s = substr($_, 0, $length); $s => ++$u_ids{$s} } @{$ids_ref};

    if (scalar(keys %u_ids) == scalar @{$ids_ref}) {
        return @{$ids_ref};
    }

    # fix the non-unique ids
    my @u_ids;
    my %incr;
    for my $id (@{$ids_ref}) {
        my $s = substr($id, 0, $length);
        if ($u_ids{$s} > 1) {
            die 'Length too small' if length($u_ids{$s}) > $length;
            #this string could be not unique!!!
            $s = substr($id,0,$length-length($u_ids{$s})) . ++$incr{$s};
        }
        push @u_ids, $s;
    }
    return @u_ids;
}

my @ids = <DATA>;
chomp @ids;

my @u_ids = unique_ids(10,\@ids);
warn Dumper \@u_ids;

__DATA__
A2990_duallayer_1
A2990_duallayer_2
A2990_duallayer_3
A2990_duallayer_4
A2990_duallayer_5
A2990_duallayer_6
A2990_duallayer_7
A2990_duallayer_8
A2990_duallayer_9
A2990_duallayer_10
LXP_01
LXP_02
LXP_03
LXP_04
LXP_05
LXP_06
LXP_07
LXP_08
LXP_09
LXP_10
LXP_11
LXP_12
LXP_13
LXP_14
LXP_15
LXP_16
LXP_17
LXP_18
Normal_1
Normal_2
Normal_3
Normal_4
Normal_5
Normal_6
Lenoc3_carina_A
Lenoc3_carina_B
Lenoc3_carina_C
Lenoc3_duallayer_1
Lenoc3_duallayer_2
Lenoc3_duallayer_3
Lenoc5_carina_1
Lenoc5_carina_2
Lenoc5_carina_3
Lenoc5_duallayer_1
Lenoc5_duallayer_2
Lenoc5_duallayer_3