I'm sure you are getting differing answers because companies handle it differently and have filed different guidelines with the state Insurance department. First, the answer will vary based on whether or not the Insurance policy being proposed is a Commercial policy or a Personal policy. With a commercial policy, the answer from most companies will be yes, you can put both on the same policy. The only thing that could present a problem would be if the two buildings had different uses (one residential and one an office building for example) but even then, most commercial policies can handle multiple locations. I gets trickier with Personal policies. Most personal policies for a rental building will only be able to handle 1-4 unit buildings (a couple can do up to 5 or 6 but thats rare). Also, many of the personal policies can handle only one building or one location.
I've insured similar situations before in the Personal are but usually it ended up with 2 policies. One situation was a home with a separate single family on the property. I was a able to find a company that would cover the Liability for both buildings on the homeowners policy and insured the building and loss of rents for the other building on a separate policy. In another situation, we had to do a home and a commercial policy for client that had his business in a detached barn building. In that case we insured both policies with the same insurance carrier so that, if there was a claim, there would not be two different companies arguing over who needed to pay the claim. There are probably other combinations to handle your situation but without know what the two buildings are being used for and who the company insuring it I would just be guessing.