Rent prices

[Shawn Pappas]

I am in the process of buying a duplex. 3 bedroom 1 bath in each unit. Both units are occupied with long term tenants. One(lower) has been there 21 years and other(upper)has been there 5 years. Rent down stairs is 485 and upstairs is 600. Seems like a big difference for each unit when there doesn't seem to be any added benefits. Is this okay to do? There is room in rental market raise rents, but with two long term tenants I am wondering if that would be a bad move? Any suggestions?