While I will not pretend to be an expert, I think I can speak with confidence when I say their will be no problem with that at all. My first two bat houses were occupied in five weeks and were placed side-by-side. Pictures on this post
first-timer-bats-in-five-weeks-have-questions-t742.htmlAfter getting my first bats I got pretty interested in the little guys and began doing a lot of research. As it turns out placing the bat houses in the manner in which I did may have actually increased the odds of occupancy. Apparently in many species of bats the males and females want to roost near each other but not actually with each other (yes...there's definitely some humor in that!). They will prefer roosting locations which allow for this. Also if you look up bat houses on YouTube or sites like like it you will be able see video of thousands of bats emerging from bat houses that are literally mounted side-by-side and may number 10-12 houses. Clearly if your location has good sun exposure and you are allowing adequate landing and takeoff room under the houses then the more the merrier!