Thanks! Robert Rottmerhusen explains why 3rd party manufacturers
are changing the LensIDNumber in their lenses:
"The reason why the 3rd party manufacturers are using different ID's now is the
focus adjustment feature of newer Nikon pro cameras. This feature uses only
the one byte LensID to recognize a lens (again) and this was almost one
number in the past with these lenses."
So the reason is to differentiate their lenses for the new focus adjustment