My wife and I bought a duplex as our first house in 2010 and I believe it was one of the best financial decisions we've made. Depending on where you live of course, I think a duplex as a first home is almost always a win-win. We still live our duplex, occupying the slightly larger unit while the tenants pay the mortgage. I'm not sure what your particular area is like, but here there are a lot of duplexes in the more historic areas so there are state and local tax credits we took advantage of when we renovated the place. Plus, you'll receive all the tax benefits that come from owning rental property. As an owner occupant there are usually fewer laws you need to abide by when searching for a tenant; you can be picky as they will be essentially living on your property, but do check your state and local laws first.
Some people wouldn't consider owning/ living in a duplex because they want their own house and it would feel too much like sharing. Our house is split as first and second floor apartments which I think helps in making it feel separate, plus since we live in the lower unit, only we have access and use of the backyard. (Something else to remember is to put in the lease who has use to what might be considered public areas, i.e. the backyard, garage, etc.)
I'm not familiar with your area so it's hard to judge how good $1,500/mo from your pocket is. What would a single family house with a $1,500 mortgage be like? Is it even possible in your area? I'm having a little trouble understanding your numbers, but let's say one day you move out and rent both units, you would have a positive cash flow, correct? If so, that's great and I would say go ahead, if not I would recommend against it. You'll find cash flow is everything with owning rental property. I think your plan to start with a duplex is great! Get the hang of being a landlord, and then in the future move on to something bigger, i.e. a quad. You might even discover being a landlord is not for you, but feel good in the fact you will then own a highly sought after rental property.