Odd VIN observation, '92 100S

["Craig D. Niederst" <niederst@telerama.com>]

While installing my O2 sensors last evening, I noticed a VIN stamping in an
odd place, behind the engine on the upper part of the firewall (right above
the V6 marking on the engine cover on a small white section of the
firewall). The VIN reads WAUZZZ4AZNN122064. But on the data plate on the
dash, and on the sticker inside the driver's door, the VIN reads
WAUBJ54A2NN122064 (with a build date of 5/92). Anyone else seen this on
their 100, or any other Audi for that matter? Doesn't the ZZZ marking mean
an official Audi test car, or something like that? TIA.

Craig
'92 100S (76k)