The "ghost text": text deleted from a docx file reappears in the InDesign-imported text

I sent the pdf files of InDesign-formatted text to the editor. He was surprised by finding in the layout the huge blocks of texts he had previously deleted from the source docx files. When I checked the source, the "ghost text" wasn't there. It was undetectable with the search tools. However when I pasted the file in InDesign, the "ghost text" popped up again. I tried to copy-paste the text in a new docx file, and the result was the same. The only way to get rid of the "ghost text" was to paste the text only, yet then I lost the footnotes.

Apparently the "ghost text" reappearance makes the editor's work going to pot as we can not be sure how deeply it impacts the edited text. I've never encountered such a problem. Please, help.