I dont know how to easy clone a complete layout. Maybe by 'hacking' the layout XML's. Might be a case of 'search and replace'. But that is totally out of my league.
Your goal is always producing a code, events, a script, how ever you wanna call it. Excuse me for anticipating on what follows on the cloning.
In my humble eyes is a copy of a layout, and reusing a lot of the code preferable above a clone of the layout and having to recode everything.
If you gonna make templates, my opinion is that you should use families and families only. That way you can very easy replace objects and keep kinda everything in place.
Menu's are a lot easyer to do with 1 Global Layer, another tip.
But hey, i might be wrong, and wayyyyyyyyyyyyyyy of a topic that started with UID's.