Two new members we added a couple of months ago keep showing up exactly three times on every calendar event we create. Typically these are setup to invite everyone.
This is an old bug that seems to have held on even in the new version of TT. The dev team is aware of it, as I recently reported it to them as well. If you really want to fix it the only way I have found that always works is to change the invitees to a smaller group that does not include the new person, perhaps a single Den/Patrol/Unit or even just a single person. Save the Event, go back in and then invite everyone, that has always fixed it for me. Not very helpful when you have many events. Hopefully once they finish quashing bugs with the new version they will be able to get to the member resolver and get it fixed once and for all.