Zoning v Property use

[Jeff Prather]

I'm under contract on a property. Its zoning is single family but its property use is duplex. It has separate meters (water and electric). It was built as a duplex and zoned for a duplex at that time. The zoning changed many years later. Metro codes is saying its not grandfathered because the same person's name appears on the electric company records for both sides for several years. Has anyone had a similar experience or does anyone have zoning knowledge to share? How big of a concern is this? Would it cause you to walk away from the property?