use strict;
use warnings;

my %seen;
my @array = (["1", "1", "3"], ["1", "5", "6"], ["1", "1", "3"]);
my @unique = grep {! $seen{$_->[1]}++} @array;

print "@$_\n" for @array;
print "\n";

map {$_++} @$_ for @unique;

print "@$_\n" for @array;
print "\n";