For this to work you have to completely REMOVE one perl -- or install in another location -- this is the "safest" way
If you use the zip installer from http://downloads.activestate.com/ActivePerl/releases/ you can have multiple perls in different directories. Well, provided you edit Installer.bat before running it, so it doesn't pollute the registry
## FORGET THESE
sub create_registry_entries
{ return warn "FORGET registry";
sub create_file_association
{ return warn "FORGET association";
sub create_script_mapping
{ return warn "FORGET IIS";
sub update_path
{ return warn "FORGET diddling path";
sub remove_html_shortcuts
{ return warn "FORGET html";
sub Set
{ return warn "FORGET REGISTRY ";
Also, you want to install 5.10.1 and NOT 5.10