I used the same layout but changed the background image every time.
The background change was simply the addition of the console logo, nintendo, sega, etc.
I believe in Mala you have to name the menu the same as the emulator, so nintendo is nintendo, etc.
I would just open the mll file switch the background and save as.
It's work and not that easy to set up.
I'd like a more simple was as the amount of work to do what I did was I'd say about 3 x more work.