PHP multidimensional array merge recursive

function array_merge_recursive_ex(array $array1, array $array2)
{
    $merged = $array1;

    foreach ($array2 as $key => & $value) {
        if (is_array($value) && isset($merged[$key]) && is_array($merged[$key])) {
            $merged[$key] = array_merge_recursive_ex($merged[$key], $value);
        } else if (is_numeric($key)) {
             if (!in_array($value, $merged)) {
                $merged[] = $value;
             }
        } else {
            $merged[$key] = $value;
        }
    }

    return $merged;
}