Here are what the records of the Hunt Co., Chicago, looked like, for this period anyway. They were written on envelopes with a sample chip inside.

I have no dupes.

The one on the left is a "BR" hotstamp on a red-brown chip which has the 20 link, oval chain mold.
The one of the right is a red FOE chip with a mold not in Borland or Herz -- 16 squared, flat chain links.

Robert