Created attachment 139707 [details]
Example file saved by Word 2013

If we create a document with a chart in a footnote in Word, and save it as DOCX, then reopen the file in LibreOffice, and save it again, it causes a broken file and Word is unable open it. 

Steps to reproduce:
1. Create a new document in Microsoft Word.
2. Create a short text with multiple footnotes.
3. Insert a chart in one of the footnotes.
4. Save the document as DOCX and close Word.
5. Open the file in LibreOffice, and save it again with a different filename as DOCX.
6. Attempt to open the file created with LibreOffice in Microsoft Word.

Actual results:
Charts multiply every time we save the file in Writer as DOCX and reopen it, and Microsoft Word is unable to open this DOCX file.

Expected results:
Charts shouldn't multiply, and Word should be able to open the file.