Steps to reproduce:
1. Open user attached project
2. Start a new scene
3. Go to top menu and click Test/Create Scene A
4. Save the scene
5. Start a new scene and click Test/Create Scene A again
6. Save as a new scene
7. Compare both scenes with a diff tool
8. Observe the file content is different

Expected result: the produced file should be the same. If the input is identical, the output should be identical as well.

Reproduced in: 2017.3.0b3, 2017.2.0f3, 2017.1.2f1, 5.6.4f1