Repeated checking of documents. Paper duplication checking refers to the repeated detection of papers, that is, whether there are words, sentences, paragraphs, etc. In the same paper as other people's documents, so as to determine whether the paper is the original. Paper duplication checking is a very important part of academic paper writing, which can help the author avoid being identified as plagiarism by universities, academic journals or publishing houses because of high repetition rate, thus ensuring the quality and academic value of the paper. Paper duplicate checking is usually carried out by professional duplicate checking software tools, which can automatically compare the similarity between papers and existing documents and give detailed test reports and repetition rate data. Paper duplication checking is a very important link in academic paper writing, which can help the author to ensure the quality and academic value of the paper. In the process of writing, the author should avoid repeating the content as much as possible and adopt appropriate quotation and expression to ensure the originality and academic value of the paper.