Listed as Triplex, but has 5 rental units (nonconforming) ??

I found a multifamily home that is listed as 3 Units, but it states that there are 2 additional non conforming rental units, for a total of 5 on the property. Would non-conforming still allow me to rent the unit legally? What legal issues could I run into? Should I consider these 2 units in as total rental revenue when crunching numbers?

Thanks!