为您测试以下筛选器工作：

function wpse245094_fist_duplicate_slug( $slug, $post_ID, $post_status, $post_type, $post_parent, $original_slug ) {

    // slug had to change, we must have a duplicate
    if ( $original_slug !== $slug ) {

        // try to replace `-2` with `-es`
        $new_slug = preg_replace( \'#-2$#\', \'-es\', $slug );

        if ( $new_slug !== $slug ) {
            // if a replacement occurred ensure uniqueness again. 
            $slug = wp_unique_post_slug( $new_slug, $post_ID, $post_status, $post_type, $post_parent );
        }
    }
}

add_filter( \'wp_unique_post_slug\', \'wpse245094_fist_duplicate_slug\', 10, 6 );