A family of Microsoft word processing software products for creating web, email, and print documents.
There are two articles on the Word MVP website that contain macros for deleting duplicate paragraphs (not sentences or phrases) within the active document:
Delete duplicate paragraphs using a Range object
https://wordmvp.com/FAQs/MacrosVBA/DeleteParaRnge.htm
Delete duplicate paragraphs using a Selection object
https://wordmvp.com/FAQs/MacrosVBA/DeleteParaSel.htm
They differ only in the technical detail that the first one uses a Range object and the second one uses the Selection object. The Selection is visible on the screen, while a Range object is not visible.
The macros both assume that the duplicate paragraph occurs immediately after the first one, which is probably not what you are looking for. Finding a duplicate that occurs later in the document would require a slightly more complicated code. Also, both of the macros immediately delete the duplicates, and don't pause to let you see what was found. That could be modified as well.