my @results = nonunique_intersect(\@temp, \@temp2);

# ...

sub nonunique_intersect{
    my ($a1, $a2) = @_;

    my @unused_list = @$a2;
    my @results = ();

    for (@$a1){ # For each element in the first array...

        for (my $i = 0; $i < @unused_list; $i++){ # Search for it in
                                                  # the 2nd array...
            if ($unused_list[$i] eq $_){ # if found, add to results,
                                         # remove from unused list.
                push @results, splice @unused_list, $i, 1,
                               (@unused_list[$i+1 .. $#unused_list]);
                last;
            }
        }
    }

    return @results;
}