Well, it mostly happens with the students, either for the submission of multiple assignments or for submitting a manuscript in an international journal.
I just would like to provide a brief explanation about this topic.
If a student submits the same paper to multiple assignments in the same class, those submissions will not match each other, thanks to the default self-match exclusion.
However, a self-match can occur when a student submits the same paper to assignments in different classes where at least one of the assignments is set to save papers to the repository. This is because papers submitted to different classes are not automatically excluded as self matches
Self-matching may also occur when an instructor submits a student’s paper as a non-enrolled student to an assignment. If the student had already submitted that same paper to the same assignment or elsewhere, then the instructor’s submission will match the student’s paper 100% and vice-versa if the student submits their own paper after the instructor’s submission (as a non-enrolled student). Submitting papers as a non-enrolled student does not affiliate any link to the actual student user.
It is similar to the case of submitting a manuscript in a journal. If the journal uses the same Turnitin/ithenticate account under a university where the students or faculty members are in there, then self-matching is identified. The journal editor and the students/faculty members submit the same document to the same Turnitin/ithenticate account.
It also happens with a dissertation/thesis. When you submit your dissertation, it will be checked using Turnitin/ithenticate automatically. After that, you submit a manuscript to the journal that uses the same Turnitin/ithenticate account. You can tell me what happens next!
Please note that one organizational Turnitin/ithenticate account will have multiple users but with the same database. So, if I use my account from the Faculty of Nursing and my friend uses another account from the Faculty of Engineering, and we submit the same document/paper, then 100% self matching occurs because both users use the same organizational Turnitin/ithenticate account, although they are from different faculties.
So, there are only two solutions to this: 1) the instructors need to understand how the Turnitin/ithenticate works for students’ assignments, and finding a journal that does not use the same organizational Turnitin/ithenticate account for submitting a manuscript, or 2) enjoying paraphrasing your work.
Note: Deleting a paper from the assignment inbox does not remove it from the Turnitin database. Therefore, a paper deleted from an assignment may still come up as a 100% matching source on another paper’s Similarity Report.
Hope it helps!
Another info can be seen at Turnitin Support Center.
This is an open access article distributed under Creative Commons Attribution 4.0 International (CC BY 4.0)