Array
(
    [0] => Array
        (
            [product_id] => 512
            [category_id] => 149
        )

    [1] => Array
        (
            [product_id] => 512
            [category_id] => 156
        )

    [2] => Array
        (
            [product_id] => 512
            [category_id] => 351
        )

)
Array
(
    [0] => Array
        (
            [product_id] => 512
            [category_id] => 149
        )

)