what you have to do is make one side of the double doors that you have "inactive" which is done by flush bolts or cremone bolts. These bolts engage into the floor and into the jamb head and lock the door in place. Intall these on the inside of your room. Once ingaged you can then lock the other door with any sort of bolt, doorknob, hook or whatever. This allows you to go in and out just the one door, but when you have to move out something big you disengage the bolts and use both doors. PM me if you want to go into further detail. I am a designer at a custom door company and have seen it all.