Mutlipe Custom fileds order by

Hi :
I’m writing a query_post like this .

$args = array(
        'post_type' =>  DEBBING_TYPE_SLUG,
        'post_status'   =>  'publish',
        'meta_query'    => array(
            array(
                'relation' => 'AND',
                'status_clause' => array(
                    'key'       => '_debbing_status',
                    // 'type'      => 'NUMERIC',
                ),
                'order_clause' => array(
                    'key'       => '_debbing_order',
                    // 'type'      => 'NUMERIC',
                ),
            )
        ),
        'orderby' => array(
            'status_clause'       => 'DESC',
            'order_clause'     => 'DESC',
        )
    );

query_posts($args);

And use query monitor the sql is below :

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID
FROM wp_posts
INNER JOIN wp_postmeta
ON ( wp_posts.ID = wp_postmeta.post_id )
INNER JOIN wp_postmeta AS mt1
ON ( wp_posts.ID = mt1.post_id )
WHERE 1=1
AND ( ( wp_postmeta.meta_key = ‘_debbing_status’
AND mt1.meta_key = ‘_debbing_order’ ) )
AND wp_posts.post_type = ‘debbing’
AND (wp_posts.post_status = ‘publish’
OR wp_posts.post_status = ‘private’)
GROUP BY wp_posts.ID
ORDER BY CAST(wp_postmeta.meta_value AS SIGNED) DESC, CAST(mt1.meta_value AS SIGNED) DESC
LIMIT 0, 10

Every time i reload the page ,the result is different .

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