php check for duplicates in array

1$arr = array(1, 4, 6, 1, 8, 9, 4, 6);
2
3$unique = array_unique($arr);
4
5$duplicates = array_diff_assoc($arr, $unique);
6
7print_r($duplicates);
8Array ( [3] => 1 [6] => 4 [7] => 6 )

1$counts = array_count_values($array);
2            $duplicate_title  = array_filter($array, function ($value) use ($counts) {
3                return $counts[$value] > 1;
4            });

1function has_dupes($array) {
2    $dupe_array = array();
3    foreach ($array as $val) {
4        if (++$dupe_array[$val] > 1) {
5            return true;
6        }
7    }
8    return false;
9}