My main app - Beyond Compare, a file diff-merge utility from Scooter Software(and a really good one at that) has some spiffy rules that let you 'do the diff' on versions of an excel document.
You can compare (and it seems now you have merge as well) excel as well as word files. I haven't really compared word docs yet but xls diffs work ... well!
All you gotta do is download the rules (as a zip).
- Unzip it to your Beyond Compare install Directory.. MSExcel folder for the xls diff rule.
- Run Beyond Compare.
- Main Menu > Tools > Import Rules. Select the rule file under the MSExcel folder.
- Select the two xls files in Windows Explorer, right click and choose Compare! voila!