NYC 2 fam Townhouse- do units need to be separated?

[John Smith]

We are looking at a rental property in NYC (townhouse) for long term investment/eventual gut renovation.  It is laid out like a one family but is a legal two on the CO.  There are two building entrances- 1st floor unit with garden access and 2nd/3rd floor unit.  We are figuring out minimum necessary changes before we would be able to rent out the units.  Right now, there are no doors separating the units, but there are two kitchens.  Would we need to add a door/wall separating internal staircases/units?