Si tengo una matriz multidimensional en PHP como así ...

    [0] => Array
    (
        [url] => http://domain1.com
        [domain] => domain1.com
        [values] => Array
            (
                [character_length] => 25
                [word_count] => 7
            )

    )

    [1] => Array
    (
        [url] => http://domain2.com
        [domain] => domain2.com
        [values] => Array
            (
                [character_length] => 30
                [word_count] => 7

    )

¿Cómo puedo fusionarlos para producir ...

    [0] => Array
    (
        [url] => *can be anything*
        [domain] => *can be anything*
        [values] => Array
            (
                [character_length] => 55
                [word_count] => 14
            )

    )