Add parameter to attachment url

functions.php

add_filter( 'wp_get_attachment_url', 'grola_wp_get_attachment_url', 10, 2 );
function grola_wp_get_attachment_url( $url, $post_id ) {
    return add_query_arg( 'p2', $post_id, add_query_arg( 'p', $post_id+1, $url ) );
}