I have a user that has a local replica of their mail DB. Once a in a while a handful of Calendar Events will re-appear back in their Sent Items. These “Phantom” calendar events are from the past year and were deleted way back when.
Subject: RE: Phantom Calendar Events showing up in Sent Items
That the replica needs a fixup/compact/updall… Try that and see what happens, if they are not on the server replica, then delete the local replica and redo-it…