Since I didn't imagine overlapping objects would be very common, I didn't implement a way to chose which object to select. Normally, the start position should not be right where the door is, if the door itself is properly linked to a door in another level, you'll exit the right door anyway when you enter the new level, and the starting position will be ignored.
In the default FiNCK world, you'll see that it's very rare that the starting position will overlap with a door object.