One of you guys will need to use or create a different Google account (whose password you've both written down!), then go to his Google+Local page and click the "Manage this page" option on the right-hand side of the page, and then follow the steps for verification from there.
Having the two listings may be trouble if they're at the same address and aren't officially/legally two separate businesses (I don't know one way or the other whether that's the case here). Might get you into hot water with Google, such that IF they're not two legally separate businesses, you may have to nuke one of the listings. But I'd suggest claiming both of them first.