I occasionally find two versions of the same episode being simultaneously downloaded - this happens when Sonarr finds and grabs an upgraded version of the episode while the originally grabbed download has not yet completed. When this happens, it would make sense for the download already in progress to be automatically cancelled, as the file will be replaced by the upgraded file anyway.
the problem is that some jobs never complete, for various reasons, so automatically cancelling all previous downloads of that ep could be problematical for some people (it might have been the only valid download there was).
you could potentially have sonarr cancel any remaining same or lower level quality jobs, that it also started (presuming it keeps track of that), when it imports a file?
that would save some bandwidth - im presuming this is the main reason for the request? but i dont think you can have it cancel anything at job submission in case the new job never completes (and the cancelled ones might have).
either way it would need to be a user enabled option
The main reason would be so the download of the upgraded file can complete faster, since it wouldn’t have to share its bandwidth with the already downloading file. Cancelling after the newer download had completed wouldn’t help with this.
It doesn’t happen all that often, anyway, so I suppose it doesn’t matter too much - it’s just annoying on the odd occasion when I’m waiting for a download, and find it’s been slowed down by having two alternate versions downloading at once.