There are about 10 different sections of my town and an identical home will sell for very different prices in each. 

It seems like it would be difficult to get such data as finding identical properties and tenant prospects at the same time, situation, etc.

But I would be circumspect about how I requested the records (need them for personal research project), how the information appeared when disseminated (all indications that it came from the State would be removed), and how I phrased my interactions with property owner's who were identified through use of public records (I'd never mention that the owner's identity or address was obtained from the State or County, only that obtained the information legally at considerable cost).

At least that way there's verification of identity. 

We own an identical duplex literally across the street in the same condition that brings in $800 per side so there’s room for improvement.

1) You have to allocate purchase price to all four(equally if they are identical) If you don’t, what would be a cost basis of the last unit?

Somehow, these details were easier to manage when we were just building two identical houses at a time!

However a home around the corner identical to my 3 bedroom 1 full bath and 3/4 bath in master suite sold for 127000 In Feb.

If you take two identically designed policies (One a Whole Life and the other an IUL with the same premium and same Death benefit, ), the IUL will most assuredly outperform the Whole Life. 

I lost soooo many deals haggling over $5k here and $10k there because I had just bought an identical house for less the week before.