Exclude Multiple Post Thumbnails From Post Attachments

by 

     $thumb_id = get_post_thumbnail_id(get_the_ID());
     $bg_id = MultiPostThumbnails::get_post_thumbnail_id('work', 'background-image', $post->ID);
     $args = array(
       'post_type' => 'attachment',
       'numberposts' => -1,
       'post_status' => null,
       'post_parent' => $post->ID,
       'exclude' => array($thumb_id, $bg_id)

      );