Get references and check for shadowed files before opening a model

If I open a model with load_system() I eventually get a lot of warnings caused by referenced dictionaries, libraries, etc. that have shadowed files on the path.

How do I find all those shadowed files before using load_system() so that I can take care of those shadowed files and eventually remove them or from the path?

(Clearing the whole path is not acceptable!)

Thanks for your suggestions.