I never have this situation since I believe that each application should only have exactly one .cgi file acting as gateway for the browsers. The rest of the business processes are implemented in modules. In the server side, decisions are executed by method calling, not URL dispatching. Playing with HTTP specs somewhat PITA for me. But I can understand if you run into such situation by inheriting some legacy codes.

BTW, thanks for providing information on the POST redirecting thing (++). As the page you refer to says, I'm one of them that don't realize the fact. OTOH, I rarely use redirection to respond a request. Upon reading the page, I'm glad that I don't rely on POST redirecting. I think I would make some modifications on the application structure instead of trying to provide a single form that can be handled by more than one CGI program. It just doesn't make sense to me.