Jak zdobyć tablicę, nie podmijaj elementów w PHP

$input = array("a" => "green", "red", "b" => "green", "blue", "red");
$result = array_unique($input);
print_r($result);

//result
Array
(
    [a] => green
    [0] => red
    [1] => blue
)
Homely Hare