Is there an existing issue for this?

• I have searched the existing issues for a bug report that matches the one I want to file, without success.

Did you read the documentation and troubleshoot guide?

• I have read the documentation and troubleshoot guide

Environment

- **OS: Ubuntu 20.04**
- **Sage Version: 9.8**

Steps To Reproduce

No response

Expected Behavior

Labels of selection list should be unique.

Actual Behavior

You can select more than one label from a selection list.

Additional Information

No response