Unidentified Rebel Technician is an NPC, a Rebel technician who was forced to wear a badge that identified him as "Unidentified R. Technician" because he'd lost a bet.
The Enemy Let Slip Edit
R2 decided he was leaving now. He was asked if he was leaving in the Falcon. R2 replied that he didn't want to fry in that death trap and he'd take Luke's X-wing. 3PO told him to be careful. A Rebel technician fit R2 into the X-wing. R2 asked the Unidentified Rebel Technician why his name tag read, "Unidentified R. Technician." The Technician replied that he lost a bet.