You could probably just add to the "Logged in as user" rule to include admin.
Really just about any technique is possible, but I would think that would be the easiest solution to that problem.
You could also add a group for super-admin to the users so that you could create any number of super-admin users. It would mean tweaking the admin login page and adjusting the security rules accordingly.
There are no docs on making that change, but you should be able to delete the existing page and use security assist with the new implementation.