Best way to protect ADU rental with insurance?

[German E.]

Dear BP, 

I have a couple of ADU units in single family rental properties and am looking to make sure they are properly covered with insurance. I have received contradictory information from insurance agents - my first agent insisted that a single family home landlord insurance includes protection for a separate structure, and that it would be sufficient to cover the ADU. However another agent says the ADU is a separate dwelling, and that it is specifically not covered. He recommends a second insurance quote for the ADU. The actual language in the insurance would seem to indicate the second agent is correct, and of course insurance companies would fight to pay as little as possible in the event of a major claim.

How are investors going about this problem?  Are there multi-unit contracts that also apply for ADUs?