Duplicate invites appearing in the Outlook calendar

SUMMARY & RESOLUTION

If Outlook is configured to sync emails with your Gmail account and you receive invites to your Gmail account then you may encounter a case where the invite appears twice in your Outlook calendar. The root issue stems from both Gmail and Outlook automatically adding invites to the Outlook calendar. If this occurs at different times of the sync process then you will see the Gmail invite and then potentially the invite added to your Outlook calendar by Outlook when it receives emails from Gmail and detects the invite request.

One way to mitigate this issue is to disable the option on the Google calendar settings to automatically add invites to the calendar. This is done by editing the Google calendar settings and selecting the option "No, only show invitations to which I have responded". This means that only the Outlook calendar will add invites to the calendar and avoids the case of both Google and Outlook adding the invite a the same time.
 


Another way to avoid this issue is to enable the option to only sync meeting requests that have been accepted. When this option is enabled gSyncit will ignore the invite in the Outlook and Google calendars until it is accepted. This allows the invite to exist in both calendars outside of the sync process until it is accepted by either the Outlook or Google calendar.