It all depends on your debt to income. Also depends on the Lender guidelines. If your tenant has been making the payments for at least 12 months and can provide proof, they will not hold the mortgage payment debt against you. You can obtain and FHA loan which requires 3.5% down in which only $500 of if has to be your money meaning the rest of the 3.5% minus the $500 can come as a gift from family.... more
I would say that as long as you maintain your good credit and can show that you have received steady rental income from your duplex that it would not be an issue. A number of people own investment properties as well as homes that they live in. If you are currently looking, I would suggest that you speak with a lender about this and they would be able to give you a more definitive answer. Most any Realtor is going to want you to be pre-qualified before they show you properties so this would be an important first step anyway.