Checking for Duplicate Choices
You can check if the option set contains duplicate choices.
1. Go to the information page of the option set and click the Structure tab.
2. Click the toolbar action 
in the left pane of the Structure page.
in the left pane of the Structure page.3. The Duplicate Choices window opens, listing duplicate choices found within the option set. For each duplicate choice, you can review the options that contain that choice.
4. Close the window to take a corrective action. For example, you may want to delete or rename the duplicate choice.