Or wait I've reread your comment a few times, and now I wonder if you mean just use a common wall between the two to make two sides to the same building so I would end up with a 20 foot wide x 16 foot deep building with a wall running down the center dividing the 20 walls in half...
Oops not sure what I just did there above but ...so if I use the 10x16 size I would run them in a series but leave 10 feet of space as run between each building is that what you mean?
So if a 10 x 16 was supposed to be good for 40 birds would you recommend trying 12x18 if I have 50 to 55 birds? I wish I knew if there was anyone in MN with experience building and using these structures, last winter we had -30! Also curious if anyone has tried to use the same type of building...