Cooper,
I apologize for the disruption. The best options when you get the duplicates are to either manually cancel the meeting items or you can use the Calcheck tool to remove them. Its workaround #3 in the Known Issue article, Outlook shows conflict errors when updating or cancelling meetings - Microsoft Support. Since that calendar item is in conflict, please do workaround #2 first and then do workaround #3 to remove the duplicates. Since the conflict is only in Outlook Desktop on that machine it might be best to make updates from OWA for now and then wait for the service fix to roll out. The fix is planned to be enabled in Prod worldwide at 11:00 AM PST on 7/11/24.
Here is the service health dashboard update:
EX800425
Title: Users may intermittently be unable to update or cancel calendar items in the Outlook desktop client
User impact: Users may intermittently be unable to update or cancel calendar items in the Outlook desktop client.
More info: Users intermittently receive an error when updating or canceling calendar items that prevent these users from completing the intended action.
As a potential workaround, users can try updating meetings using the new Outlook desktop client or Outlook on the web: outlook.office365.com/calendar/view/day
Additional information on the end user experience and error messages being received can be found here: support.microsoft.com/en-us/office/outlook-shows-conflict-errors-when-updating-or-cancelling-meetings-69c26227-40ef-4377-8f12-1749fcaad2ad
Current status: The fix is continuing to roll out as planned and we anticipate it will saturate all impacted environments by Thursday, July 11, 2024, by approximately 6:00 PM UTC. We’ll continue to closely monitor the situation throughout the deployment.
An update has been made to the Support Article posted above to address certain error messages that have been reported in the Clear Offline Items workflow.
Scope of impact: This event may intermittently impact users updating or canceling calendar items in the Outlook desktop client.
Next update by: Wednesday, July 10, 2024, at 10:00 PM UTC