Add an MD5 hash to lines of data that have already been seen.

hash_data

#!/usr/bin/perl

use strict;
use warnings;
use 5.010;
use Digest::MD5 'md5_hex';

my %seen;

while (<DATA>) {
  chomp;
  $_ .= ' ' . md5_hex($_) if $seen{$_}++;
  say $_;
}

__DATA__
NAME AGE GENDER DEP-Id Company
AA 30 M IT-001 google.com
AA 30 M IT-001 google.com
AB 40 F IT-002 Yahoo.com
AB 40 F IT-002 Yahoo.com
AC 50 F IT-004 ABC.com
AC 50 F IT-004 ABC.com
AA 30 M IT-001 google.com