In general, you want one public configuration file per site. That means if you have multiple machines running WebObjects, you should access all WebObjects applications through a single machine that is running the HTTP server and that contains the public configuration file.

A new private configuration file is created automatically any time a WebObjects application is started and a private configuration file doesn't exist. The adaptor contacts only one instance of an application in the private configuration file; if you manually start HelloWorld and it's already been started, the entry for HelloWorld in the file is overwritten. (The old process will continue to run, but cannot be contacted.) The adaptor also cannot contact a remote instance of an application using the private configuration file.