They are cancelled individually on a grinding wheel by the manufacture. In this case, H.C. Edwards.
Your chips were either samples saved by HCE for reference, sent to the Sahara for approval or used as a salesman sample.

Notice how carefully the notches are positioned. They're always located in body color of the chip. Never on the inserts.
Someone who is trying to cancel a large amount chips would never take the time nor would care about the cancellation. It's easier to drill or bury in cement.

I find it interesting that the top one looks a little worn. As if it had been handled quite a bit. Most are practically new in appearance.
Sharp edges and full cross hatching.

Pete