I'll chime in and agree with Al here. I know some folks that do separate, but I personally think keeping the two together is the way to go. That flat can be a real challenge to cook it properly, without drying it out. I rotate my packers, always trying to leave the flattest part to the coolest side of the smoker.
Not saying you can't separate them, but if you are just getting started, I wouldn't.
Heck, I am doing my first pastrami from scratch, and even with that I felt a little uneasy about separating the two (but I did)...