When duplicating a stage in order to preserve the associated files in the new stage, the test file should not be copied or it should be copied as a new file, exclusive to the rest of the files.

This is helpful because if the file is indeed copied as the same file and the user updates the test file name and contents, it will overwrite the original test file. From a UI perspective I can see a user accidentally renaming this file and losing their previous content.

In addition, once a user switches files they cannot revert their changes as they are no longer saved.