Duplex taxed as commercial in the county?

[Rylan Kean]

While running numbers on a duplex I discovered that the unit has commercial taxes on it in for the county and residential for the city. This greatly increases the tax rate and affects my numbers, in fact if it was zoned residential I could make it work. Any thoughts on why it would be taxed commercial and if there is a chance to get this changed? 

I have seen this multiple times, so it might be good info to know for the future regardless.