The Chip Guide has this documented in the listing:

Casinos Austria International was the first west casino operator in the former Czechoslovakia. Owned the Casinos Czechoslovakia. In January 1, 1993, the country was separated in Czech Republic and Slovakia. Company was renamed CZECH CASINOS. The casinos used the old chips with a stamp with the new designation, until new chips were issued.

I have this chip from there and you can see it was relabled over a Casino Czechoslovakia chip. Is this what is meant by "old chip with a stamp"?