I've always been curious about these chips. I think I have a full set with the $20 and $25 chips being, by far, the rarest.
The basic story is that Benny Binion was sent to Leavenworth Prison in 1953. He arranged to have his old friend, Joe W Brown, take over the Horseshoe until his return in 1958. Brown was an experience casino operator from New Orleans. Here's a link.
https://over50vegas.com/128_Fremont_Joe_Browns_Horseshoe_Club.html
The most common story I've heard is that the name Binion's needed to be erased from the premises. By defacing the chips Benny was able to comply with that order but since he had an accurate accounting of the chips he wouldn't be cheated during his absence.
Maybe that's the full story but I've always had questions.
Joe Brown and Benny were fairly close friends. Brown knew how to run casinos. Who was Benny suspicious of? Why wouldn't Brown make new chips? His ownership was prominent on the signage and there's napkins, coin buckets etc. with Brown's name. I presume Benny must have told HC Edwards not to make additional chips but it's still not clear to me how that protects Benny. Destroying all the old chips and making a new rack is more understandable to me. Since there are no Brown labelled chips then were these chips used for the entire five years of Brown ownership? Why are they so rare? I've only seen one $25 chip in all my years of collecting (which I pried from a somewhat reluctant Campiglia). I've written to Jack Binion with these questions but haven't heard back.