Legal use of a duplex (triplex)?

[Byron Broughten]

There's a property zoned as a duplex in a two-family zone, but it's a triplex. It has three kitchens, three living spaces separated from one another—three gas meters, even. But the city confirmed that it's not legally a triplex, but rather a duplex.

My main question is: What does that mean for how the property can be used?

In this city, the occupancy limit for duplexes is 6 people per unit, and zoning told me they don't concern themselves with the number of leases at a property. Can anyone speak from experience or expertise about what issues I might have by leasing the property to three parties, given I respect the occupancy limit?