(defined $hash{$array[0]}{$id}) 
    ? ($hash{$array[0]}{$id} += $array[2]) 
    : ($hash{$array[0]}{$id}  = $array[2]);
[download]

That's more complicated than is necessary. Perl's clever enough to know that if you add a number to an undefined variable, to treat that var as 0. This would suffice:

   $hash{$array[0]}{$id} += $array[2];
[download]