Steps to reproduce:
1. Create new Unity project using Mixing Reality Template
2. Navigate to Assets > XR and select XRSimulationRuntimeSettings.asset
3. In Inspector window expand “Keys” drop-down
4. Select Element 3 > Vision OS drop-down
5. Select Android from the drop-down
6. Observe Console window

Actual results: Identical item can be added to the list, causing error in the Console “ArgumentException: An item with the same key has already been added. Key: Android”
Expected results: If the item is already added, it should be greyed out in the list, not cause any errors in the console

Reproducible with versions: 2.2.0 (6000.0.62f1, 6000.2.111, 6000.3.0b9, 6000.4.0a4)

Tested on (OS): macOS Silicon Tahoe 26.0 (M1)