> The specific reason for the retractions was copyright violation, so there was nothing wrong with the actual papers from a scientific standpoint.

There is a reason why the German portmanteau word "Zensurheberrecht" ("Zensur": censorship; "Urheberrecht": the related concept to copyright in German law) exists.

The so-called copyright violation was that Max Planck had published the same article in 2 journals, which was not unusual at that time, because different journals had different readerships, so publishing in more journals was necessary if you wanted to reach more people.

So supposedly he plagiarized himself.

The second retracted article was even less justifiable, because the modern editors or their automated system had believed that 2 articles were the same, but they were not, they only happened to have the same title.

Never heard this, but very accurate. thanks :)