(cross-posted from math.stackexchange.com)
I found after publication of an article that a chunk of it was duplicated in a previous article written by someone else, and I'd like to know if I should take some action, like write a corrigendum just to add the other paper as another citation. Perhaps some journals have a formal process to deal with this?
In my field, pure mathematics, it sometimes happens that people publish the exact same theorem, but the methods are distinct enough that the reviewer of the later paper views it as publishable because of its methods. In my case, only one of four theorems in my paper duplicates earlier work, but the methods I use, while looking slightly different, would certainly be considered essentially the same as the earlier paper.
I suppose the best answer might simply be, "contact your journal and ask". On the other hand, I have seen many times a result claimed as "independently" discovered in multiple papers, and I don't recall seeing a corrigendum or something in those cases. Perhaps a notation on the research page of my website is sufficient?
As a follow-up, in mathematical publishing/culture, where is the line drawn between saying a result was "independently" discovered by multiple people and crediting all of them, as opposed to give priority to the one who was first? Crediting all authors who gave substantially different proofs makes sense to me. But what if two proofs use essentially the same idea?
(This question differs from
in that the both results, original and duplicate, have already published.)