bluelines:

Unlike the mules for the GT4, GT3, GT3 RS which all sported number plates with BB EM ("Entwicklung Motorsport") the R carried the LB plates used by normal Carreras, Caymans, Boxsters, etc. This tells you who actually drove the R project, regardless of marketing talk from AP.

Nah dude, they just used the LB plate so future buyers could blend in more. At first they thought that removing the wing would be enough to allow the 911R to go unnoticed like all the clients wanted, but then they realized someone on the Internet would out them to the world based on the development license plate.