The system said the records were gone. They really were gone. But the same system routinely reports counts that are wrong by a factor of eight — so how do you know which kind of "gone" you are looking at, before you act on it?
Every bulk job gets re-run — after a crash, a false failure, or a nervous operator. Whether that re-run heals the data or doubles it comes down to one question you answer before it starts.
The message said the record was created. It was not. A different message said the save had failed. That one was already in the database. The interface was wrong in both directions on the same afternoon.