To be fair, there’s a difference between Apple QA issues and local problems. If a large number of Macs suffer from some problem, it’s Apple’s responsibility and it’s a QA failure. If a handful of Macs suffer from some weirdness, it’s probably related to some local configuration or corruption and thus not something Apple would be able to fix.
Such as I have with installing any security update on my iMac, through multiple macOS versions.
It might be interesting to look in System Information > Software > Installations and see if it’s really being installed twice or if the first install is failing for some reason.