Infographic from the Text Recycling Research Project to determine if your text is duplicate publication.
“Text Recycling is the reuse of textual material (prose, visuals, or equations) in a new document where (1) the material in the new document is identical to that of the source (or substantively equivalent in both form and content), (2) the material is not presented in the new document as a quotation (via quotation marks or block indentation), and (3) at least one author of the new document is also an author of the prior document.”
Hall, S., Moskovitz, C., and Pemberton, M. 2021. Understanding Text Recycling: A Guide for Editors. Text Recycling Research Project. Online at textrecycling.org.