Archie,

None of the Mirage chips say Las Vegas or Nv on them.
I feel certain Andy is right about Paris recieving special permission, not to use NV.

The NV Reg says all chips must have the City and NV on them, unless special permission is recieved from the Commissioner of the Gaming Commission. Meaning the "Big Dog" only can give it.
If Steve Wynn got permission, there is no reason Aruthor Goldberg could not have gotten it.