#!/usr/bin/env perl -l

use strict;
use warnings;

my @data = (
    [ qw{E123456789 G123456798 h12345} ],
    [ qw{E1234567 E7899874 G123456798 G123456789 G123456798 h1245} ],
);

for my $scope (@data) {
    my %seen;

    for my $identifier (@$scope) {
        print $identifier unless $seen{$identifier}++;
    }
}