Check out Deja vu, a database of similar Medline citations developed by a team at UT Southwestern Medical Center.

“Deja vu is a database of extremely similar Medline citations. Many, but not all, of which contain instances of duplicate publication and potential plagiarism. Deja vu is a dynamic resource for the community, with manual curation ongoing continuously, and we welcome input and comments.”

See “A Tale of Two Citations” in Nature 451, 397-399 (24 January 2008) | doi:10.1038/451397a .