4. The method of claim 1 , wherein determining the candidate similarity score includes: determining that a text phrase on the first page matches a text phrase on the second page; and adding a first amount to the candidate similarity score based on the determination that the text phrase of the first page matches the text phrase on the second page.
7. The method of claim 4 , wherein the text phrase on the first page is located in a header of the first page or a title of the first page.