func_areaportal

Areaportal do not occlude anything even when the doors are closed. It may be because I placed them next to each other, but the Valve Developer Wiki says nothing about it. Areaportals in Hammer Areaportals in game Areaportal configuration

Is this... not allowed? I know that if you have, say, two doorways on the same wall and they both have areaportals covering them, they'll be merged into a single one when the map compiles. But if one of them, for some reason, is a func_areaportal_window, does this cause problems? I ask because...