It's Perl. PERL is a shibboleth.

But on topic: What happens when it doesn't work? How do you know it failed? What was the error message?

Most likely, you can just install the rpm over-top and it'll work fine. If you really want, you can remove the perl lib dirs. Where those are located depends on your install, but it's probably something like this: /usr/lib/perl /usr/share/perl /usr/local/lib/perl and /usr/local/share/perl... hard to say.

Try: perl -e 'print "@INC\n"' to get a list of these locations.