I receive notification mails
Although I didn't work on this challenge...
The badges are assigned to me; I didn't only get a wrong mail:
A colleague also told me that he was getting notification mails about earned devtoberfest badges even though he didn't register to devtoberfest.
Plus: The share on twitter link generates a tweet with this text:
But you have registered for Devtoberfest by joining this very group. You wouldn't be able to post in this thread if you hadn't joined. So, you are receiving that badge for having joined this group. The other badges are for tutorials that are part of Devtoberfest. We give credit to everyone who has completed the tutorials in the past since it's not possible to complete them again.