in reply to Change package name on the fly?
You could build and install the same version of Perl on your system twice. Just when you run Configure to build and install your second version use --prefix=/some/where/else. Then install the module you want to test in both Perl's. Something like
Then in your test script just change the shebang.$ /where/you/put/bin/perl -MCPAN shell cpan> install NWCLARK/Foo-Bar-0.02.tar.gz ... $ /some/where/else/bin/perl -MCPAN shell cpan> install NWCLARK/Foo-Bar-0.01.tar.gz