There is no quick and easy solution to determine which Mogilev is the right. All available sources, primary, e.g. census records and family registers, and secondary, e.g. business directories need to be consulted just to see where a name in question was known to exist.
Moreover, "a citizen of N" does not necessarily mean that a person, or even his father, lived in that town. It was difficult to change the registration officially, so a Jew could be a registered resident (more accurate translation) of N, but live in O and P, and his son could move to Q and R and still be a registered resident of N.
Zharov is not that uncommon name which was used by both Jews and gentiles. There was, for example an immensely popular, as Russian as they go, movie actor, Mikhail Zharov. He had a Jewish connection, actually: wife No. 4, Maya Gelshtein.
FAST Genealogy Service