Go straight for a 4-plex, far better deal.
4 units is the maximum size that still qualifies for a standard mortgage, so you don't need to pay commercial rates. It gets even better if you actually LIVE in one of the units as owner, and manage the rest.
Buy right, and get the right tenants (ones that won't bother you for every, little thing, just because you live right there, you have to set boundaries right away), and it's easily possible to live with NO personal housing costs of your own, and even make some money.
Good luck having a duplex even come close to covering your mortgage costs, and then you are at the mercy of a single renter not paying if you can't carry all the costs yourself. Spreading those costs to 3 separate renters in the 4-plex, is much smarter.
P.s. Look for buildings that have separately metered apartments, it's worth paying a little more. If you pay common heating or water, etc, there's NO incentive for your renters to control their heat or water use to save costs.