The reason I ask is because, I have seen two other versions of this not-in-use $1 chip for Circus-Circus, Las Vegas, both of which are categorized as "prototypes". Other than inlay design differences (all from the same artwork), mine differs in that it is notched.

Courtesy of Greg Susong's Nevada Ones website, as posted there courtesy of Dick Bartley and Ernie Mollinari, respectively.

Thanks,

Jim