Once you copy a project with MyStories these MyStories will be copied over as well. Even if you delete the report users, the MyStories won't be automatically deleted too. 

So once you recreate the same users, it can reconnect the users again (if they still exist in the Dapresy database (for example because they have access to other projects)). 

This can be used when you would like to make changes, but you don't want to do this immediately in the live project. You can copy the project, delete the report users, make your changes, upload the users again, and delete the users in your live project.

Note: keep in mind that in case the report users made changes to MyStories in the live project after making the copy, these changes won't be available in the new live version.