Keep in mind that in MAME, you can map just about anything to just about anything, on a per game basis.
That means that you can build a 2 player control panel, with 2 typical joysticks, one for each player, but, for Battlezone proper, you can map player1 joystick to the left tread control and player 2 joystick to the right tread control.
Another great example is SMASH TV or Robotron. Those games used 2 joysticks, one for move, one for fire. But, if you build a typical 2p CP, you can just map P1 stick to MOVE, and P2 stick to fire (or whatever you want).
If I'd realized that up front, I'd have never put a diagonally mounted 4-8 way stick for qbert and such on my cab (I'd have just mapped my U360's to mimic that behavior), but, ah well, live and learn.