"cloning" (sort of ) an installation

[Alan Evans]

Please excuse my inane question. I'm fairly experienced with
administering RH/Fedora installations, but I've just never tried to do
this before.

I'm setting up a backup server which is to have substancially the same
packages installed as the primary. I can easily enough get the list of
installed packages on the primary with "rpm -qa", but how do I turn
that list into something that will as automatically as possible
download and install/upgrade packages on the secondary? Or is that
completely wrong-headed?

Am I making sense? Like I said, I am pretty competent with most
administrative tasks and using the command line. I've just never tried
this before and have therefore never thought seriously about how to do
it.

-Alan