Your unit having its own electric meter is just one of those things BUT with the way 911 systems are tied to addresses ( there should be a 2nd address number posted if a second housing unit is present and not the same structure) being that you also have learned that the address is supposed to be a single family residence tells a lot , meaning the other rental unit and yours likely are not approved to be used as rental units - to be lived in as separate housing units [ your cities zoning rules are what count so even in the case of a older in use unit that fell under a so called grandfather clause the records for the address should say there are two units there] ( as to the 2nd electric meter , yours you didn't say if that's the only meter for electric or not, it is a possibility that for some odd reason like maybe a run from home business or office that the second meter was installed ( but if you pay the LL for your electricity and not the electric company then I wonder if the meter is a customer owned submeter ) but in the end what really counts is what your city says about the number of housing units that are supposed to be at that address.