When uploading multiple documents using the Zip File Upload method, Turnitin automatically compares the text content of each document within the ZIP file as the documents are uploaded.
If a document in the ZIP file is an exact copy of another one already processed in the same upload batch, the system flags it with the message "This paper is a duplicate".
Files marked as duplicates are automatically excluded from the final submission batch to prevent redundant submissions.
Note: Files identified as duplicates do not necessarily have the same file name. Turnitin checks the content of the papers for duplication, not the title.