Duplicate entries in calandar

Question

how do i delete duplicates without selecting them one by one

Answer 1

Hi Barry Milner, 

I understand how inconvenient duplicate calendar entries can be, especially if there are many of them. At this point, I recommend that you review and try the steps provided in the AI-generated answer on your thread. That reply typically includes the most relevant checks for this scenario. 

To help narrow this down, could you please let me know the following: 

• Do you see the duplicate entries only in Classic Outlook for Windows, or also in Outlook on the web? 
• Is this happening in one calendar only, or in multiple calendars? 
• Did this start after any recent change, such as re-adding the account, importing calendar data, changing devices, syncing with a phone? 
• Are the duplicates affecting all calendar items, or only recurring meetings/events? 
• Are new duplicate items still being created, or are these only existing duplicates from earlier?

While my initial response may not fully resolve the issue, I truly appreciate your cooperation as we work together toward identifying the most effective solution. Thank you so much for your understanding. 

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Answer 2

In classic Outlook for Windows, duplicate calendar items can be removed in bulk by switching the calendar to a list view and deleting them together, or by using the CalCheck tool.

Method 1 – Use List view and delete in bulk

1. In Outlook, go to Calendar.
2. In the Navigation Pane, select the main Calendar folder that has the duplicates.
3. On the View tab, in the Current View group, select Change View > List.
4. Click the Subject column heading to sort items by subject so duplicates group together.
5. Use Ctrl+click or Shift+click to select groups of duplicate items.
6. Press Delete to remove all selected duplicates at once.

To avoid future duplicates when importing calendar data, use File > Open & Export > Import/Export, and choose either Do not import duplicates or Replace duplicates with items imported instead of allowing duplicates.

Method 2 – Use CalCheck to automatically move duplicates If there are many duplicates or they are hard to identify, the Calendar Checking Tool for Outlook (CalCheck) can find and move them for review:

1. Download CalCheck: Download Calendar Checking Tool for Outlook from the article "Outlook shows conflict errors when updating or cancelling meetings".
2. Create a folder C:\calcheck and extract the CalCheck .zip into that folder.
3. In C:\calcheck, open calcheck.cfg in Notepad.
4. Set DupGlobalObjectIDs=true and set all other tests to false, then save the file. This ensures only duplicate items are targeted.
5. Close Outlook.
6. Open Command Prompt, run:

      cd \calcheck
      calcheck.exe
   

   Select the Outlook profile that has the duplicate calendar.
7. Open C:\calcheck\CalCheckErr.csv in Excel to review the duplicates list.
8. Close Outlook and Excel.
9. In Command Prompt, run:

      calcheck.exe -F -R
   

   This moves the duplicate items into a new Calcheck folder in the Outlook folder list.
10. After confirming the calendar looks correct for some time, right‑click the Calcheck folder in Outlook and select Delete Folder to remove the duplicates permanently.

Note: CalCheck is powerful; leaving other tests set to true can move non‑duplicate meetings, so ensure only DupGlobalObjectIDs is true before running it.

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References:

• Delete duplicate calendar items
• Outlook shows conflict errors when updating or cancelling meetings