Describe the bug

When using <EuiComboBox /> with a delimiter prop and adding duplicated values, the component adds all values.

Impact and severity

Low severity. I found the issue when adding this component in our application. It's a nice to have.

Environment and versions

• EUI version: latest
• React version: 18
• Browser: Chrome
• Operating System: Mac

To Reproduce

1. Go to the Combo box with "With delimiter" section.
2. Paste this value: "a, a, a, a".
3. Press enter or focus out the component.
4. All 4 values are added.

Expected behavior

Only one value needs to be added.

Screenshots