I'll let wyvern give you a for sure answer on this but in my programming experience it will depend on if they are using SendMessage to send false keypresses and mouse movements to a window or if they are using keybd_event mouse_event to simulate keyboard and mouse events.
If its the first and they are using sendmessage then it should be as simple as running two copies of xunleashed one pointed at each copy of daoc.. course then again this would depend on how they are getting the hwnd of the daoc window if they are using this method.
If they are using the latter and simulating keyboard and mouse events then I dont think it would work. But I also doubt they would be using this one because if they were you would then be able to run an xunleashed macro go to another window and the macro would press the keys in the new window.
And then again its very possible that Wyverns and the rest of the programmers, skill in this area are ahead of mine and they do it a totally different way that I dont know about

Thats why I say I'll let Wyvern give you a for sure answer.. but for the time being you could probably try running two copies of unleashed to see if it works. (If that is even possible with the registration keys)