Ken:
I'm afraid I can't give you any ironclad answer to this because I tinker mostly with assembly language (on arduino clone hardware).
As TchnclFl mentioned, you have to start two instances of the LCD library which I think you would do somewhat like this:
LiquidCrystal lcd1(12, 11, 5, 4, 3, 2);
LiquidCrystal lcd2(12, 10, 5, 4, 3, 2);
(note that the Enable lines are assigned to different pins)
I have been wanting to try this for a while - I'll try to do something this afternoon and get back to you. It will give me an opportunity to use the real Arduino that I got in the Sparkfun free day.
Don