I think you bought one box of them, so maybe they were sample chips. The old USPC used to advertise in their catalog prices for all sorts of combinations of inlaid chips, as custom orders. They had different letters for, I guess, usually, someone's first and last name. They often had a picture (die-cut design) on one side and an initial on the other. They were poker chips, so the color was the main thing. I guess the combinations would hinder ringing in chips not paid for. I'll post some pictures of chips like that that I have. Less common, I found, is a number on one side and a letter on the reverse.
Robert