Not quite 3-2-1 Backup at the time however I have resilient copies of DVD backups from 1999. Both still work. I did become fully 3-2-1 backup compliant years later when I made an ISO on a hard drive and then backed that drive up.
I can’t bring myself to part with one of these. And on top of that I have the same double backups for every year throughout the 2000’s on DVD.
No I do not have a good answer why I didn’t purge this before I moved to another continent.