How to reproduce:
1. Open the user's attached "BugTitlebar" project
2. In the project window drag the "bugreport" Asset from the "Assets" folder to the "Assets/Editor" folder
3. In the Project window select the "New Container Asset"
4. In the Inspector select and drag the "Sub Asset (Sub Asset)" container's name to the Project window

Expected results: No action can be done
Actual results: The Editor tries to move the already moved file giving the "Failed copying file" error

Reproducible with: 2019.4.18f1, 2020.1.17f1, 2020.2.2f1, 2021.1.0b2
Could not test with: 2018.4.30f1 because of the CS0246 and CS0103 errors

Notes:
- The issue can also be reproduced by dragging Components to the Project window