Fair enough, how about just making it clearer in the documentation? Currently you need to look at the source code to see what would be required for a signature clash to occur. Maybe something like:

Note that the [os.stat()](https://docs.python.org/3/library/os.html#os.stat) signatures only consider [st_mode](https://docs.python.org/3/library/os.html#os.stat_result.st_mode), [st_size](https://docs.python.org/3/library/os.html#os.stat_result.st_size), and [st_mtime](https://docs.python.org/3/library/os.html#os.stat_result.st_mtime). In some circumstances it's possible for differing files to be considered equal when _shallow_ is `True`.