<?php

$array = Array
(
    0 => Array
        (
            0 => 'Walter',
            1 => 'White',
        ),

    1 => Array
        (
            0 => 'Marie',
            1 => 'Schrader',
        ),

    2 => Array
        (
            0 => 'Marie',
            1 => 'Schrader',
        ),

    3 => Array
        (
            0 => 'Hank',
            1 => 'Schrader',
        )

);

$results = array();

foreach ($array as $k => $v) {
        $results[implode($v)] = $v;
}

$results = array_values($results);
print_r($results);