sometimes file could have multiple file paths,
e.g. mapped drive path vs UNC path on Windows:
Z:\Media\file.mov vs \\Server\Media\file.mov
Watchtower considers these files different (same way as Premiere Pro & After Effect does). By default Watchtower will always use UNC path for import.
If you manually imported file via mapped drive path, Watchtower will import it again, but with UNC path.