It would be real easy to do something like this. All you would have to do is open the xml file for that hotbar, copy all the relevant code twice over, then on each copy, alter the name, id, and positioning of the hotbar, and there you have it, three copies of the same exact bar.
I've just did what you want for you and uploaded the result as an Addon to MaddyCraft. Unfortunately I had not much time to test it, so use at your own risk.