Bud Jones made the 1st coin inlays in 1973.
The Frontier inserts are available in mass quantities at flea markets. Anyone can and does easily pop out the coin on any BJ chip and pop in the frontier coin.
Thet are fakes.
They are counterfits made to fool US.
The sellers fully know what they are selling.
I have 3 examples of these chips. I stopped picking them up after I seen how many different were being made.