One small hint for you. If you do put in an offer for the property, do so with a contingency that the owner gets a signed and certified letter from the zoning office allowing the "duplex". If you wish for some other use of the property, then it would be up to you to see if other zoning is allowed, but put a similar contingency in the offer.
Contact me if you have any questions.
Century 21 Associates
Cell (Preferred): 877.614.1494