For some reason I Sonarr decided to download about 50 already downloaded and indexed episodes… Will update more details but it’s running on a Synology using the 17th March version. Has been working correctly for at least a month prior.
Episodes weren’t real or fixed etc versions, and were from all over the series lists.
If they were monitored and the cutoff wasn’t met then its doing exactly what it is supposed to.
Double check your cutoff for the profile(s) attached to those series and you can use Wanted -> Cutoff unmet to see if there are additional files that have not met the cutoff yet (which would have Sonarr watching for releases).
Ahh, I now understand… It’s not just a case that the episode’s already been downloaded, but it has to meet the quality/size specification in the profile or else it tries again later… Sorry about this, and thanks for the answer… 
Does this mean if it finds a better version, it’ll pull it down, even if it’s a got a valid one? Do I assume it will continue to do this? Because it’s damn’d annoying, it ate another 10G of downloads today.
If the cutoff hasn’t been met or its a proper/repack then yes it will download another release.
Change the cutoff in your profile/unmonitor the old episodes to prevent Sonarr from looking for upgrsdes.
Nope, this is finding dvd releases which have a higher priority than the webdl releases and so downloading them… I’ll look to change the cuttoff tonight and see how it goes. Thanks again 
If DVD has a higher priority than WEB-DL and the cutoff hasn’t been met then its working as expected.
If you need any more help on this a screenshot of your Profile would be helpful, as well as the activity for an episode in question.