After my paper was published, I discovered an error and contacted PLOS ONE to have it fixed. Now my paper shows up twice in PubMed. Is this a mistake?
If your paper had a formal correction, this is not a mistake; your paper will be listed in PubMed twice.
If a published paper contains a significant error, we publish a Formal Correction to fix that error; the Formal Correction is its own publication and therefore has its own DOI. The Formal Correction then receives its own, separate entry in PubMed in order to link to the original correction on the PLOS ONE website. The correction’s title will include the word “Correction” followed by the original paper’s title. PubMed mandates that the original and the correction both be entered in its database, as you can see here.
Please note that your corrected paper will show up only once in PMC (PubMed Central), because the correction will be embedded in the PMC entry for the original paper itself.