I have the chip without the overstamps. I got it from Rip Poulos who operated illegals in Biloxi area.
There is some info about it in my Biloxi articles. Your chip is in part 2.

http://www.marlowcasinochips.com/links/genetrimble/genetrimble.htm

The Fiesta was open from 1950 to 1993 and was closed to make way for Treasure Bay. It was owned by John Mladnich. It was the first club on the coast to offer entertainment, year around. Like Gus Steven's Supper Club, the gambling was moved to private clubs when liquor was legalized along the coast.

All of the old distributors created floor sweepings to test new hot stamps before running new orders.