No you dont have to use different .torrent names but you have to use correct tracker URL. Each torrent tracker have different URL. When you add torrent file to rtorrent you shoul point movie folder as torrent download folder so it can check the file and start seeding. If movie in your personel computer and you want to seed from seedbox then yes you should send movie to your seedbox.
When you creating torrent file fill source section with tracker abbreviations so this will provide different hashes* for torrent files and you can add .torrents to rtorrent as different torrents.
*Filling with different things also provide different hashes but filling with tracker abbreviations is the most preferred method. For example if you are creating .torrent file for "Filelist" fill source as "FL" if you are creating for "TorrentLeech" fill source as "TL"