My mantis installation should have a public and private area. The public area contain several projects/subprojects. If someone adds a new issue, it gets a new issue number out of the official pool. These numbers gets documented outside.

To track internal issues e.g. concerning the installation, new users and their rights or something like that, I want to configured a project therefore, but this project normally also interferes with the "public numbers".
I'd wish that projects could have there own numbers. How is this possible.