Reproduction steps:
1. Create a new project
2. Create > Material
3. Select newly created Material and open Shader selection menu by clicking on the Shader dropdown in the Inspector
4. Observe the Shaders

Actual result: Some Shaders are duplicated
Expected result: Shaders are not duplicated

Reproducible with: 6000.0.65f1, 6000.3.4f1, 6000.4.0b4, 6000.5.0a4

Reproduced on: macOS Tahoe 26.2 (M4)

Note: Both Shaders show up as selected in the Shader selection menu if one of them gets selected