Update Rollup 1 for W2K: weirdness

I downloaded MBSA 1.2.1 (in old posts, people said it's better than 2.0
to diagnose this problem with Update Rollup 1 still showing up in the
Windows Update list), and it says that my computer is missing updates
823559 and 891781. According to Windows Update, the only high-priority
update I need to install is Update Rollup 1 (and I installed that
already). So I checked the KB article for Update Rollup 1, and it is
supposed to include both of those updates (823559 and 891781). I guess
when I installed Update Rollup 1, those 2 updates didn't get installed
for some strange reason. I'll have to try to re-install it. Can I
just re-install Update Rollup 1 over the existing installation, or do I
need to uninstall it first? I'll be using the 31 MB executable file
that I've downloaded and saved, and not Windows Update, if that
matters.