In Coming of Age (STNG S1E19), we meet Mordock, who is then understood to be the first Benzite to be admitted to Starfleet Academy.
Later, in A Matter of Honor (STNG S2E8), we meet Mendon. Mendon is a Benzite and a Starfleet Ensign who joins the Enterprise D as part of Starfleet's Officer Exchange program.
As Benzites who come from the same geostructure, Mendon and Mordock look very alike. On first meeting Mendon, Wesley Crusher mistakes him for Mordock. It is in this scene the root of my question is presented.
As stated, Mordock is the first Benzite to enter Starfleet Academy. However, when mistaking Mendon for Mordock, Wesley comments that the Benzite could not have possibly graduated Starfleet Academy already.
Was Mendon ever actually a member of Starfleet during the events of A Matter of Honor, or simply an acting Ensign during his participation in the Officer Exchange Program? If the former, how did he become a member of Starfleet without going through the Academy?