How to remove/uninstall custom installed perl modules?

Question

Hello all.
Yesterday I upgraded from 10.3.7 to 10.4.5, then started to reinstall a bundle of perl modules (via the Terminal and 'perl Makefile.PL -- make -- make test -- [sudo] make install').
As I saw too late, some of those modules I installed are now part of the standard OS X installation -- now some perl modules are twice on my machine, the 'originals' (so to say) in '/System/Library/Perl/5.8.6/...', and the 're-installed' are -- as usually -- in '/Library/Perl/5.8.6/...'.
My questions:
(1) Can these duplicates do any harm while executing perl code?
(2) Is there an easy way to get rid of the duplicates (e.g., move the associated files in '/Library/Perl/5.8.6/...' to the trash)?
Fortunately I have saved the terminal output of every installation, so it should be easy to find everything that was changed.
Any advice is appreciated -- thanks in advance.
Joerg
G4/400 PCI (Oct. 1999) w/ 1 GB RAM & 128GB internal drive, Pioneer DVR-110D   Mac OS X (10.4.4)  

Answer 1

Perl has a list of paths it searches when it needs to find a given module, similar to how the shell uses the PATH variable. If the things you installed are in a directory after that which contains Apple's official stuff, your stuff is invisible. Check the section labeled "@INC" in the output of 'perl -V'...that list is searched top-to-bottom.
If what you installed is ahead of Apple's but what you installed is at least as high a version number as Apple's, again no problem in general. The modules Apple supplies have genereally quite stable API, so there's no problem if a program expects Appl'es but gets yours instead. OTOH, if you have a lower version, there could be trouble, since things may rely on the features only present in new versions (something for a certain OS X would reasonably assume "the stuff that came with that OS X" as a minimum).
Anything you installed manually you can remove manually as well, using "rm" or dragging stuff to the trash. Modules often install a .packlist file somewhere in $arch/auto/ in your perl lib dir.
I think you can often do '[sudo] make uninstall UNINST=1' to uninstall, assuming you kept the original builds or feel like redoing 'perl Makefile.PL' in the exact same version of the modules you installed. However, the 'uninstall' target is generally frowned upon by perl folks.