FullDescription via Excel upload

i am trying to import products via excel.

I am getting an error when I am trying to add the FullDescription column. If I remove the FullDescription column from the excel, it works fine. I manually added FullDescription and put two words in it and I am still getting this error - "An item with the same key has already been added."

My import works fine with ShortDescription but as soon as I add the FullDescription I get this error.

my version is 3.8

please advise, thanks!

Make sure FullDescription column should not more than one times in your excel file.