You might also not want to actually “fork”, and clone and push a new repo instead. Otherwise the repos are connected, and you have to one day ask github to remove the connection because there is no button for that. It takes a day or so.
Edit: to clarify the main problem with having a fork is pull requests go to the original package by defualt.
I was using “fork” in the sense of “take the code and start a new project without intention of submitting changes back to the original”. I was not aware of Github attaching a special connection to using their “fork” button; thanks for the clarification.
If the old codebase is still used and maintained and you intend for them to coexist then you need a new UUID (otherwise they are the same package). The situation about an identical name has not come up, and I don’t think we have discussed this. However, I know some tooling, e.g. Registrator, can not handle it at the moment.