Nice find. The design on the wide rim was used on all other years.
Perhaps this was changed to help make it not look like a quarter? These were hated by the public. Thus had a short run. Brought back in 1999 and changed to the gold colored coins in 1999 with the SAC design. But during the change over, some cross overs happened.
Probably a mint assisted error. There were a lot of strange alterations going on at that time and an employee was dealt with.