I guess I'll call it a duplex?

[Jimmy Watts]

I've been searching my area for potential rentals, primarily multiplexes. I came across one that was listed as a duplex or maybe it just said 2 units. Anyways here's the deal: it is one parcel with 2 houses on it. The (attached) garage for one house is directly behind the other home.  They both need some attention.  I haven't looked inside them yet but before I get too giddy I'm looking for some advice. 

They are 2 different houses with separate addresses attached to the same plot. It is listed for just a little bit less than what SFR's on that street are selling for. Since it's 2 for 1 then to a novice it sounds like a steal! Right?

If the numbers work I plan on keeping it indefinitely but eventually I may need to or want to sell it. Will this be a problem when that time comes?