I don' think it's used in CPAN.pm (though I might be wrong), but I know that Perl 6 uses the "authority" trait (?) on modules, because it permits multiple modules of the name.

Actually Perl 6 has a long or full module name, which includes the short name, the version and the authority.

There's no reason why only one developer in this whole wild world should be allowed to chose the wonderful name Foo for a module, and there's no reason why you shouldn't be able to use two different Foo modules at the same time in your program, just because they happen to have the same short name.

See S11: Versioning for details