@giant-beam yea so it's basically how i said, you installed bo1 and waw into the same game folder. waw iwds only go up to iw_27 so delete iw_28 - iw_41. Also delete localized_english_iw07 - localized_english_iw14.
Problem is you probably also have a bunch of bo1 files in the zone folder, this won't matter as the game won't try to load them like it does with iwds but it's a waste of space and creates a mess so best option would probably be to delete the entire game folder and re-download waw to a new empty folder. Then do the same with bo1.