I think I understand what you did and understand what you want to do. I don't have a sure fired answer to any question on behaviors, I can never tell for sure what a flock will do. If you are going by the magic numbers quoted on here as to how much roost length they need per chicken you may find out they really don't need that much.Part of my brain tells me that they would be more likely to do so if I cut an opening at about where the square (don't give me a hard time, it's kinda a square) is and extend the roost there. I think by doing that they would think it's part of the same roost and may spread out.
If it were me I'd do both. Cut the hole so it's not an issue. Remove the door to improve your access and that opens the entire area better for the chickens. Or is there some reason you don't want to remove the door?