Help: SAXException: [word/document.xml line 2]: Attribute w:val redefined

Please, guys! Help me, I have an exam in a few days! Now I explain: Last night when I finished working on the pc, I saved the original file, plus I saved another one as a precaution (for past reasons I knew it could happen to me! today happened!) this morning, as soon as I should have started working, the file would not open anymore and I appeared this inscription:
An error occurred while opening the file. This may be caused by the corrupted contents of the file.
Error details: SAXException: [word/document.xml line 2]: Attribute w:val redefined
Proceeding with the import may cause data loss or corruption, and the application may become unstable or crash.
Do you want to ignore the error and continue uploading the file?
Yes - No

pressing No:
File format error in
SAXParseException: '[word/document.xml line 2]: Attribute w:val redefined
', Stream ‘word/document.xml’, Line 2, Column 56098(line,col).

Pressing yes: "It only makes me see 3 pages!"
Will it be because of the windows updates (which I did yesterday)?
It will be for what it will be, but guys, help me! Please!

See my comment to for the regex to fix duplicating attribute problem. If you have a reproducible scenario, please file a bug report with a sample file attached, and steps needed to turn it into an invalid.

For anyone on linux running into this problem, the easiest way to solve it is to use mikekaganski solution, but using Visual Studio Code and removing the first backslash from the regrex. That is:

  1. Get Visual Studio Code (it’s free, runs on linux)
  2. Unzip you document with unzip yourfile.docx
  3. Open the file word/document.xml in visual studio code
  4. Go to Edit->Replace and enter (<[^>]+)([\w]+:[\w]+="[^"]+")([^>]+)\2 in the first box and $1$2$3 in the second
  5. Go into the directory where the docx was unziped. should contain the word directory and your original docx
  6. Move your original docx somewhere else
  7. Re-zip it with zip -r newfile.docx .

This should do the trick.
There’s probably some way to do it with sed… but the different regex dialects are beyond my understanding.