It's VERY important to understand that the screens are very unlikely to match each other exactly. After calibrating both, you'll check them and see which one matches your pro lab prints most accurately. That's the one you'll use for editing on - the other one will be for panels, email, etc.
It's also critical to remember that the screens have to be set to "Extend", never "Duplicate".
I'm sure you already know this, but I wouldn't be doing my job properly if I failed to mention it.