Reproduction steps:
1. Open the attached project "ReproProj"
2. Open UI Builder
3. Select "Project" in the "Library" block
4. Expand "Custom Controls (C#)"
5. Expand "UI Test" group

Expected result: All groups are unique and sorted
Actual result: Duplicate group names are present

Reproducible with: 6000.0.71f1, 6000.3.11f1, 6000.4.0f1, 6000.5.0b1, 6000.6.0a1

Testing environment: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested

Notes:
- Expanding one instance of a group toggles another group with the same name (expanding the first "Group A" toggles the second "Group A", same for the "Group B")
- Group contents are incorrect: "Group A" contains only "Element3" ("Element1" is missing)
- Results may differ if the order of type declarations is changed, indicating potential order-dependent processing or unstable grouping logic