Dear forum readers,
I just happened to download three one-file torrents where the file names where identical (but the infohashes and file contents were different). Once finished there was only one file. As expected, renaming one through the torrent properties window, then choosing to verify local files put the two other torrents in error (missing files), showing they were effectively wrongly sharing the same file.
I suggest that file/root container name be checked before download, and in case another torrent has the same file/root container name, it's prepended with a random value, and re-check for conflicts until it's resolved.
Another option would be to systematically prepend the file/root container name with the infohash (possibly a checkbox in the preferences), hence no need to check for conflicts.