I think it's a bug, it should have matched by id only. But your report will be ignored because I've changed these database implementations multiple times (uncovering many bugs that lead to duplicated copies being stored) and in the end I've decided that I don't want to support Badger anymore.
I'm surprised you even managed to export all the notes given that the version you're using would try to load everything into memory before printing and if you had too many that would cause a crash. On the other hand there was a hardcoded limit of a million notes per query when using the eventstore CLI that you couldn't bypass, I guess that prevents the crash.
