In E4M1 (Ultimate Doom) there is the door with the red key in east part of the map. This door (after finding the red skullkey) can opened only once, it closes immediately and then it can never be opened anymore, even when you opened the door and don't enter.
Summary: It opens once and close immediately forever.
Imho the door should stay open. Look also at:http://www.youtube.com/watch?v=ej9f227sm3Y
Platform: openSUSE 11.3 and Vavoom 1.32 from repo with wadfile from Ultimate Doom (I bought this box many years ago).