First of all, one possibility is to duplicate other people's research work. When writing a thesis, graduate students need to make a thorough literature review of the existing research in related fields and ensure that their research work is unique. If there are duplicates of articles published by other scholars, they may be identified as plagiarism by the duplicate checking system.

The second situation is self-plagiarism. Self-plagiarism means that graduate students reuse their previously published or submitted research work at different stages or on different occasions. Although academic circles have different views on self-plagiarism, on the whole, reusing one's own research results may be considered as academic misconduct.

The third case is that the reference format is incorrect. Citation of other people's research results is an important part of academic research, but it must abide by strict citation format norms. If the citation format is wrong or incomplete, the duplicate checking system may identify this part as duplication or plagiarism.

The fourth situation is the problem of language expression. Sometimes graduate students may borrow other people's language expressions or words without making proper quotations. This may also be identified as plagiarism by the duplicate checking system.

In order to avoid the above mistakes, graduate students should strengthen their reading and understanding of the existing literature before writing their graduation thesis, and clearly express their research results in the thesis. In addition, when quoting other people's research results, we should follow the standard citation format and quote them in appropriate places.