Working with a broker who represents multiple carriers is probably the way to go in this case.

I've pretty much narrowed my choice down to two companies, Besco Air which uses Rheem and Air Blue which uses Carrier. 

Some personal lines type carriers will cover a 3 family, but most will only cover to a duplex.

Since we don't work directly for any carriers, you can call your agent first and ask if filing a claim is the right option for each scenario. 

My agents have requested quotes from a multitude of markets, big and small, only to hear that the carriers have no appetite for this type of risk.

Juan,If the 2 family is owner occupied in one of the units, the correct policy with most Insurance Companies is a Homeowners form (the standard policy form is HO3 with most carriers).  

If that's not enough, insurance carriers don't like "old homes" and the majority will not engage coverage on them - while those who will do so at much higher premiums.Here are the main issues with older homes so check the seller's disclosure on these:Electrical. 

I always get a builders risk policy on my rehab and hold properties.Pros- you have insurance coverage since the regular carriers won't give you a homeowners policy without a tenant.Cons- if you go past the term (3 months for mine) before you have renter in place (or within 30 days of having a renter) you have to buy another 3 month policy, no shorter terms are available.I got a 3 month policy from American Family for $258.

@Jack Gibson Carrier

In my opinion, getting your insurance cancelled and having to find another insurance carrier would be "undue burden."