Certificate of Occupancy Issue. Help!

[Camden Orologio]

Hello everyone, hope all is well. I am currently selling a home for a client and have ran into an issue. With COVID delaying many normal processes the procedure of getting a FOIL has been greatly delayed in NY. The homeowner had insured us that the property was a legal two family and the town had told us that it was as well. When we recieved the FOIL we have no supporting information of the property being a legal two family. The C of O from 1976 say it is a 2 story single family dwelling. The property is classified as a 220  (two family) and they have been paying taxes as such for thirty years. If this property is not a legal two family why is being taxed as such? Does anyone know what I can do to clarify this situation? THis is a great investment oportunity that is going for a great price and mostly all of our interested buyers are looking at it with hopes of it being a two family.