One of my first estate appraisals was a wide house that set over the property line. Everyone told me it must only be one site (two 50x100 lots). And I like a dope appraised it accordingly. A real estate broker snatched it up, went to the city, pleaded he could seg off a site with a tappered lot line adjustment and viola, he created a new site, built a new house on it and sold the old house too. Made me feel like a dope. Total violation of set-backs for fire safety which specified 5' on each side for both properties. Every time I drive by it, it looks like a fire trap that shouldn't have happened.
I've seen more cases where zoning created two lots when it looked like one than I care to count. Oregon actually just passed a law that re-zones all single family zones from one house to one house or a duplex (have you heard of the housing/rental shortage?). I once saw a 50 x 50 built on, then sold off that was with a 50x100 and a 50x50. So I've concluded, cities only care about tax revenue and they will let you build anything, anywhere, just so they get their taste.
Your situation even seems simpler.