array_merge_recursive_ex.php

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;
}