Skipping Footnotes

I have an issue with footnote numbering. I am using a document that has been edited by various users using track changes. In the above-the-line footnote numbers the numbering is normal (. . .52, 53, 54, 55 . . .). However, in the footnotes bellow-the-line my numbering is ". . .52, 54, 54, 55, 56 . . ." I have tried renumbering the footnotes from 53 on beginning with 53. When I do so the numbering changes to ". . .52, 105, 106 . . ." I've tried created a section break. When I show the track changes there is no visible footnote in between. What I suspect happened is that the sentence was deleted by an editor and the author copied and pasted the same sentence back into the article with the footnote from the original document. Does anyone have a suggestion to fix the problem?