Q: Is it duplicate publication if the same paper is published with different ISBN numbers?
My manuscript was accepted as a conference paper and got published on the conference’s official journal and proceedings. In addition, this paper was meanwhile published in the conference’s Selected Proceedings, which had a different ISBN number than that regular proceedings. Is this considered as duplicate publication or any form of misconduct?
ISBN numbers are identifiers that are assigned to text-based monographic publications such as books, book chapters, journal articles that are made separately available, etc. As per the ISBN website, each different product form (e.g. paperback, EPUB, .pdf) of the same content should have separate ISBN numbers. By this logic, different versions of the same content would have different ISBN numbers. So I don't think having a different ISBN implies duplicate publication. In your case, the Selected Proceedings of the conference is a special publication that includes a few specific articles handpicked from the conference's official proceedings. Thus, all the articles in the Selected Proceedings would definitely have been a part of the official conference proceedings. It would definitely be clarified by the conference organizers or publisher that there is a content overlap between the two books or that one consists of material extracted from the other. I don't think you need to worry abut duplicate publication or any other ethical concerns in this case. However, if you are still in doubt, you can write to the conference organizers seeking a clarification.