When you fetch this torrent, you could simply untick the older files that you might already have and download only the latest ones.
In addition, there are a few more reasons for sharing in this way-
Sometimes we share revised subtitle files and revised hard subbed files. That’s why we generally share the full batch of files every time.
If you are downloading files in the same location always the torrent will detect files that haven’t been downloaded and so you can recognize new files in the full batch. Also, if your folder has those files already, then while your torrent client downloads new files, the older ones will be shared with other downloaders. This really helps us since our torrents get more seeds this way for faster file sharing.
If there are any new comers, it’s easy for them to see how many files are subbed already.