Below can be the possibilities for getting incoming email twice in Outlook

  1. Selecting incorrect Outlook folder while configuring account.
    • Please select the Outlook folder of same account which you have configured in outlook
  2. Check from the admin panel, if any forwarding is set to/from the mentioned email ID
  3. Rules configuration is incorrect
    • Due to incorrect rules, Outlook builds duplicate data in the mailbox
  4. Multiple Outlook accounts
  5. Corrupted OST/PST files
    • OST/PST files are important files that contain all your Outlook data including emails, contacts, and calendar data. If these files are corrupted, it can lead to duplicate emails in Outlook. To fix this issue, you can try repairing the OST/PST files using the Scanpst.exe tool. This inbox repair tool is a built-in tool that comes with Outlook and can fix minor issues with OST/PST files.

After checking above points, still issue persists. Please check any issue at server end.

Inform L3 team for the same.