There’s are also two 2 flats next door that are “legal” that are identical to ours.

Let's say we have identical multifamily buildings, units of 2.

Our neighbors across the street with a nearly identical home said theirs recently appraised for 670, while another similar one down the street sold this winter for 580.

(Insurance should cover issues/damage between roommates such as theft; having renter's insurance).

Think of the terms "buyer's market" and "seller's market" identically to when you are thinking about the underlying real estate itself -- does the home have 40 offers all over asking (seller's market), or just 3 offers and all 3 are lowball (buyer's market)? 

I just dealt with an almost identical transaction the other day (sibling in prison included) and the property had a bunch of tax liens on it making it worthless once the liens were paid off.

Neighbor sold two days ago, identical layout for $539k.

These properties are literally down the street from each other and are almost identical except for square footage.

If they also have a picture of your driver license - that's all they need to steal your identity ....

It would be identical and rent for the same amount in 2020 of 750 BRL.