I have a couple of Indexers, many a times the same nzb is present on all of them, So when a certain Nzb fails then Sonarr goes and downloads the same nzb again from a different indexer.
It would be great if Sonarr included a feature in which, If a Nzb fails, then sonarr should download all the other similar (same quality, release group) nzb’s and Analyze them by checking the message-id of the files inside the nzb and check if they are similar to the first nzb downloaded. If it finds one which is different then it should send that nzb to the download client.
Its only an extra 1-2 api calls to every indexer that too only when the inital download fails.
Also Sonarr, can first try downloading the same release of a different age (if available) before resorting to “analyzing”.