Is this the best way to do this, or sound I just manualy delete the modules from the other location ?

No, you should fix your Config, its messed up.

Modules are supposed to get installed under

perl -V:installsitearch -V:installsitelib ( /opt/openpkg/current/lib/perl/site_perl/5.12.1/sun4-solaris /opt/openpkg/current/lib/perl/site_perl/5.12.1 )

and not

perl -V:installarch -V:installlib (/opt/openpkg/current/lib/perl/5.12.1/sun4-solaris /opt/openpkg/current/lib/perl/5.12.1)