This bugged me, so I checked it. You definitely didn't have the Wiki Team tag when we did the testing according to the times of the posts. The Wiki Team group membership was removed a couple of weeks ago, and reallocated about 14 hours after you posted above that you'd received an extra notification.
I also received an extra notification at one point.
The group tagging feature has been updated, which also came with some fixes related to group-tagging.
We'll have to test this out again, please reply here if you did or did not receive a notification when tagged with one or more of your group tags.