Brien, notched chips have 2 purposes.
Salesman samples.
Submitted to gaming for approval before actual chips are released.

Manfacturers used to be very liberal in giving them out. NV gaming put the clamps on them after people managed to cash some of them at casinos.

I have well over 500 notched samples without the advertising on the back. I have seen some notched samples sell for decent bucks but very few.

I am not talking about some older notched chips that were actually notched by casinos to cancel them.