Dungbeetle servers allow different Unity projects to have separate lists of bugs, even while connecting to the same server.
You can change a Unity project's project id in the connection config window.
Since the project id is stored in config.asset, anyone who has a copy of a project also has access to the associated list of bugs.
A project developer is a name to which a bug report can be assigned in different ways.
In the Assigned tab in the overview window, bug reports are filtered by which developer is assigned as Fixer. This is the most important aspect of having project developers in Dungbeetle.