RPM simultaneously both installed and not installed?

Something went wrong when I was installing some RPM's on Mandrake 9.0 --
probably a scratch on the CD...

Now when I try to manually run 'rpm -Uvh thefile.rpm' it says the rpm is
already installed, but 'rpm -e thefile.rpm' says it's not installed.

Pretty amazing that it's simultaneously installed and not installed?

I tried 'rpm --rebuilddb' which took a long time, but did not affect the
above behaviour.

How do I get rpm to know what is actually installed?

\\/

p.s., the rpm in question is gcc... I didn't install the 'devel' tools
when I loaded the computer, and now I'm trying to install (compile) some
KDE apps, so I'm having to figure out what to load...