How to reproduce:
1. Download and open the submitted project "2DAnimTest_18_4_10f1.zip"
2. Open Fei_Cel_group Asset within Sprite Editor
3. Create a Sprite Rect and apply
4. Open Fei_Cel_group Asset within Photoshop
5. Rename a layer to the same name as previously created Sprite Rect
6. Go back to Unity and reimport the Fei_Cel_group Asset

Expected result: Names of the Sprite Rect and the layer are not allowed to be the same
Actual result: Names of the Sprite Rect and the layer are allowed to be the same

Reproducible with Unity versions: 2018.4.11f1, 2019.1.14f1, 2019.2.8f1, 2019.3.0b6, 2020.1.0a8
Reproducible with Package versions: 1.0.0-preview.4, 1.1.0 - preview.3, 1.2.0 -preview.4, 2.0.5

Notes:
PSD Importer package was not introduced in Unity 2017.4, therefore the issue was not reproducible.