This is an issue of responsible authorship
Duplicate Publications
Research that is both conceptually and methodologically sound is published with the goal of advancing many scientific disciplines. Publications benefits research by providing investigative studies for researchers to review and critique. It reduces wasted effort by allowing researchers to assess what has been accomplished, and provides direction by identifying gaps in knowledge and inquiry. Due to the limited number of manuscripts accepted for publication each year, it is essential for each submission to either represent original research, to replicate and confirm previous findings, and to make important contributions to the literature.
https://ori.hhs.gov/education/products/niu_authorship/mistakes/22mistake-a.htm
Since this has already been published but there is no issue of falsification or fraud, what IUJUR can do is to notify the researcher and the researcher's institution about the duplicate publication, as this constitutes research misconduct.
Author's misconduct inviting risk: Duplicate publication - PMC (nih.gov)
This is an issue of responsible authorship. See the COPE Guidance at https://publicationethics.org/resources/flowcharts-new/changes-authorship
Seeking prestige authorship/Gift authorship
Shamoo and Resnik (2003) state that authorship and accountability should go hand in hand. This same ethical principle should also apply when investigators seek to submit a research proposal. Prestige authorship can become an issue when there is no intention of having a high profile researcher contribute to a research proposal, study, or manuscript.
According to LaFollette, (1992), prestige authorship occurs when a person with a high degree of prestige or notoriety is listed as an author in order to give the publication more visibility or impact, even though their contribution is minimal.
LaFollete, M.C., (1992). Stealing into Print – Fraud, Plagiarism, and Misconduct in Scientific Publishing. University of California Press, Berkley.
https://ori.hhs.gov/education/products/niu_authorship/mistakes/25mistake-c.htm
https://ori.hhs.gov/education/products/niu_authorship/dilemmas/05dilemma-case.htm
This issue concerns Conflicts of Interest/Competing Interests
https://publicationethics.org/case/reviewerauthor-conflict-interest
This raises the issue of Potential Editorial Bias/Impropriety
The issue here basically revolves around whether it is acceptable for editors to publish their own work in their journals; if it is, then the review process must be made as transparent and rigorous as possible. Certainly there are examples of editors publishing studies in their own journals, particularly in those circumstances where the choice of journals is limited, as in this case. Provided every effort is made to minimise any bias in the review process by having another associate editor handle the peer review procedure independently of the editor (recognising that it would be impossible to remove bias completely), and the process is absolutely transparent, then this would be the most appropriate route to take. It was suggested that the editor send the article out for review without any names on it, but he said the subject field was so narrow and specialised that any reviewer would know who had written the paper. As an extra precaution, if and when the article in question is published, the editor might like to publish an accompanying commentary showing how transparent the reviewing process had been.
https://publicationethics.org/case/editor-author-own-journal