Deleting multiple duplicate paragraphs

I use 3 types of ai. I am paranoid about losing things, since my computer went down. I now use 2 computers and a laptop. Suddenly I find myself with multiple versions of the same things. I need a program that has enough power to analyze 300 pages, and highlight duplicates so I can delete. I also need something that will delete the two spaces I put after sentences and do it in one stroke. Because I have used different word processors, I also have break out lines I want gone.