Normally it is perfectly OK to have two different perl versions installed (as long as the installations don't overwrite each others files). The problem you're describing can be caused by having the PERLLIB or PERL5LIB environment variables pointing to the wrong library path (to the lib path of the old perl install, in this case).

If either of those vars is set, try clearing them and then re-run perl Makefile.PL etc. Also make sure that the perl.exe that gets run is the one you want to install the module with.

If this doesn't help, you might have the wrong library path built into the perl interpreter - you need to reconfigure and compile perl if that is the case.