WordPress edit_user_profile_update update secondary role

I am trying to save secondary role field in user-edit.php which is independent of WP’s main roles. I had no problem with saving other custom fields that are unique but for roles (wp_capabilities), it looks like it first saves my roles (I set sleep(10) to check in database in the process) and at the end of request, WP saves main role field which overwrites my previously saved role.