What to do:

1. Download the template you want to upload

2. Get the XML file and open in a WordPad (right click --> Open With --> WordPad).

3. Press “Ctrl + F” and in the search box type widget id

4. In every widget line it will display something like this : widget id='example1', replace that number for a any other one.
Example, if the widget says 1, erases it and place number 2 instead.
So you will have something like this now: widget id='example2'

5. Do this to all widgets you find in you XML code. When you finish SAVE(Press CTRL+S)

6. Go to Blogger --> Layout --> HTML

7. Upload --> Preview / Save

Done! Enjoy it.

Update* if you get this error bX-si9ejx, after edited your template, you should delete cookies and temporary internet files at your browser and upload template again.