Thank you very much TEEEJ, that seems to clear that up!
I knew there were 2 runways, but I had thought they were very much further apart than they actually are. I guess the planes that I see when I am approaching Roissy station from the other direction are just on a taxi-way, not the other runway. I thought the main terminal buildings separated the runways!
Thanks for helping a newbie, I appreciate the work you did to help me out with my mis-apprehension.
Cheers.