Make sure that the code is really using the same versions of the modules, and using the versions that you think it is. First, do 'rpm -q perl' on both to see which release of perl RPM you have. I am guessing that FC1 is updated and has perl-5.8.3-16. Then, add to the end of your test:

require Data::Dumper;
print Data::Dumper::Dumper(\%INC);
[download]

This will dump out the modules that it actually loaded. See if any are in site_perl directories, because then you are using locally installed versions. You might also want to print out the $VERSION for each module.