... that the CH chips were returned to the manufacturer (or never delivered) who in turn 'overstamped' them... I also heard that any issue could have the same 'overstamp' when used as samples. Resent posts (explainations) call them samples.

FACT: The few casinos in Europe who have been adding to my collection over the years, have sent me many of these examples; mostly notched, though.

There are probably other reasons why the "double exposure-type" graphics are the way they are with other casino chips... and I seriously doubt it's limited to only one reason.