This case involves four manuscripts. Three of the manuscripts were originally published in another language and then published in our English language journal. There is overlap in the authors who were involved in all four manuscripts.
The first and second manuscripts were duplicated publications from another journal. The evidence is very clear. The papers were published in another country in another language, and then in English. A native speaker of the other language was able to read both versions and found only minor differences, and the editor of the foreign language journal also did this, and recommended that our journal retract the papers. The authors checked the box on our submission form that indicated that the submissions had not been published elsewhere, and they made no mention of any previous publication in their covering letter.
For the third paper, which shares authors, we had no evidence of duplicate publication until we heard from the editor of the foreign language journal who said that it came from two other articles. However, the editor did not say in which journals these were published. Again, the authors checked the box indicating that the paper was original and had not been previously published.
For the fourth manuscript there is no evidence of duplicate publication, but it shares one author and is therefore included. The editor of the foreign language journal did not find a duplicate publication.
Two authors are in common on the three duplicated papers. The paper for which we do not have evidence of duplication has different authors for the most part, but one of its authors is also an author of two of the duplicated papers. To try to make this clear, the authorship of the four papers is as follows, where each letter indicates an author:
1) A, B, C, D
2) A, B, C, E
3) A, B, F, G, H
4) C, I, J, K, L
The editor in chief of our journal wrote to the authors (A, B, and C) telling them that they had violated international standards against duplicate publishing and received an email in reply from a supervisor at their institution, apologising for this.
We seek guidance from COPE on how to publish a retraction in our journal concerning these four manuscripts, or is another course of action more appropriate?