The replica of Travis Mayweather was a biological replica of Ensign Travis Mayweather of the Enterprise NX-01. Created by the automated repair station in 2152, this facsimile was part of the station's method to abduct humanoids to be part of its computer core. Though convincing on the surface, Doctor Phlox, while in the process of conducting the autopsy, eventually determined it was, in fact, a copy of Mayweather. The telltale sign was that certain microbes in a Rigelian fever vaccine Mayweather had had earlier should have thrived on the isolytic shock that supposedly killed him, however, Phlox found they seemed to have suffered the same fate. (ENT: "Dead Stop")
"It's a nearly perfect replica. I've never seen a lifeform duplicated in such extraordinary detail, from its epidermis down to its cellular proteins. This is remarkable work."