I’m looking at your screenshot again and if users are getting notified that they have received a badge they already have (hence causing duplicate notifications) what you need to do is check the user current badges first and only run the assign function if they do not have the badge.
If no new action is taking place, there should be no notification. So check and see if your assign badges code is running when it should not is my guess.
As far as turning off notifications all together, I only see a way to do this as a user, not a site owner. But customer support may know better on that one if you want to reach out through the bot