Outlook duplicated a meeting 16000 times

Long time reader - first time poster. 

 

I helped a user who was an organizer of a meeting and they received a conflict message regarding conflicting edits. They clicked keep all and the meeting duplicated it self 16000 times. Similar to this error https://www.assistmyteam.com/kb/multiple-edits-have-been-made-the-conflicting-edits-have-been-attached-to-the-conflict-message/#:~:text=To%20fix%20it%2C%20double%2Dclick%20the%20conflicted%20item%20to%20open%20in%20its%20inspector%20window.%20You%20should%20get%20a%20%E2%80%98Conflict%20Message%E2%80%99%20inspector%20window%20similar%20to%20one%20below. . 

 

Does anyone have any ideas why this happened? It was a reoccurring meeting with forwarding allowed. I'm not sure if this was sync issue or if the conflict message is unrelated. 

 

Additionally, any recommendations on how to organize a meeting that has participates leaving and joining throughout the year?