I'm pretty sure that I read somewhere that it's possible, but there are a few gotchas that you need to be aware of. Unfortunately, I can't find the tutorial or page that described what you need to do. I looked through the Perl tutorials, and didn't find the one that I remember reading. Could someone point me to a page or document that describes how to put multiple packages into a single .pm file?
You simply start off the new package with another package statement:
package PackageOne; # ...... code package PackageTwo; # .... more code