@Monique O. did you verify that the occupant is a life estate occupant and not a lifetime lease occupant?  

Who can I contact and what do I ask them specifically to verify?

so you've already checked with zoning to verify a 4 or 6 is permissible? 

I went over on occasion to verify the condition, but there was not a lot of evidence of it. 

Another option is to get the current tenant to sign an estoppel letter, which basically verified what he pays in rent, how much security deposit is in escrow, and that it’s a month to month lease.

Verify if the WATER & SEWER is individually metered (generally, duplexes are not).

As far as lessons, the biggest thing I've learned with this purchase was to verify lease agreements and tenants payment history.

Pay attention closely and verify the information they tell you.

You can check with the local utility about the possibility of relocating it, however eminent domain comes into play if it has been there for X amount of years so you might not have luck with that.First verify that it is on the land of this property.

They require renewal each year so you can verify the Tenant is not adding or swapping animals.