seemed to have worn out at different times, or the manufacturer was using multiple dies to strike the coins and the dies wore out in different places, causing all sorts of amusing errors.

I remember buying a set from - either Cale Guthmiller? - or Curt Squires. His story (maybe somewhere archived in the Guide) is a bit amusing as it went something like - the casino owner saw him buying up large quantities of chips and peering at them and pocketing a bunch but turning others back in. And the owner asked what the heck was going on, and when told about the "errors" - promptly escorted the Harvesting Collector out the door. One of those "Get out and never come back!" moments. There may have been a few more subtle details I am glossing over but it must have been one heck of a Chip Harvest Day.

Collectors of course are free to deal with the "errors" as they wish - try for the set (I think it's 7 or 8 varieties) - or simply understand that broken dies exist, and no big thing about that.