How to handle citing duplicate publications? I am writing a review article and have come across a number of references which were published verbatim in their entirety in more than one place (same author(s) and the same content; Duplicate Publications). All of the publications in question are before 1970 and may be divided into two classes: those that have an instance with a statement that the content has been published or presented elsewhere (which references the duplicate) and those lacking such a statement.

For those with a statement, I am inclined to cite the earliest instance and omit the later. However, the approach is unclear for those where precedence is not apparent.

I am looking for any recommendations (best practices, examples) on how citing duplicate publications should be handled in general. I have not come across an example in my literature review and have been unable to find any guidance (most search results are related to preventing duplicate publications rather than coping with their aftermath decades later).

Options I see at the moment (some of which are more palatable than others):


Don't explicitly acknowledge the duplication, but cite both variants in the text and bibliography (i.e., a parenthetical or textual citation with both instances each and every time I want to reference its/their content).
Pick one (randomly if precedence cannot be determined) and ignore the other.
Pick one (randomly if precedence cannot be determined) and include a footnote at the first use indicating that another instance exists (the alternative instance would be cited there with the full citation included in the cited references section).
Pick one (randomly if precedence cannot be determined) and modify the full citation in the cited references section to indicate that another instance exists and provide the full citation of the alternative.


Some additional, possibly relevant information:


Subsequent publications are inconsistent in which instance is cited (i.e., both are cited and precedence is often ignored).
The field is environmental biotechnology.


Edit: To clarify in response to BioGeo's answer, I cannot determine absolute precedence for instances lacking a statement because the submission dates are not included (apparently the practice was not yet common, at least in this field). Unless there is a "standard approach" of which I am unaware, the published date cannot be relied on as a general solution either, given the differing precision in reported dates. For example, consider a duplicate publication where one instance is a book chapter published in 1943 and another instance is an article in the June issue of a journal published the same year. Which came first?
The purpose of references is for readers to look up the sources of the information you present in your article. If these publications are exactly the same, word for word, then I would not worry too much about it and I would cite the most easily accessible source or the one with a DOI and only cite it once, so that it will be easier for readers to find the source without having to access some articles that are published in less accessible journals.