When a new high score is achieved, the scores dialog is automatically shown. If you click "Done", and run the dialog again, you will see the new high score; however, it is not saved to disk.

When the new high score dialog shows up, if you hit Enter key, as if you agreed with the name, the new score is saved to disk. In fact, it is saved as many times as you hit the Enter key. However, if you run again the dialog, you will only see one entry (i.e. duplicates seem to be removed).