You will have to ask your local code inspector. Every city and state is different.If you live in a small town, call the ofice in a larger city near you. I will say that if there is no codes for your area,you can do what you want, but remember that if this won't work,you have to clean up the mess.I personally don't see a problem because it's unlikely that both toilets will be flushed at the same time. Ron J.