Small multi-family property on a listing site vs zoning map

[Diego Cuevas]

When looking through Zillow or another listing site, I'll come across a duplex or 3 flat for sale that is marketed as a multi-family property, but when I pull up the zoning map for the town, the property isn't zoned in a multi-family area. Is it possible for a multi-family property to exist in a non multi-family area of a town's zoning map?