You need to look at column with this heading name : -
Short URL/English [URI/en]
Make sure every row in these cells have a unique URL. When I've had this problem I've often just appended model numbers or sizes to make sure each product does have a unique URL.
Google attaches some significance to these unique URLs so its worth spending time to think of something reasonably sensible to make each one different.
I too have noticed that the upload of non-unique rows fail so I suspect if you fix the first problem, the second one will go away.
regards
