Pretty good question. It was hundreds of duplicated entries that alerted me to the left-behind "Form 1099-B Wks" after my first simple-minded "remove import" and reimport. After deleting that left-behind "Untitled" there are no duplicates I can see. However, it's going to take a while before I can resolve some other anomalies related to the "Corrected" data in the 2nd import. That's an unrelated issue, I think; there are 907 transactions to worry about.
I had a thought about why the form for the original import got left behind. After the original import, there were "Errors" in my return in a few transactions in that import. I copied data from my normal monthly statements that was meant to correct those errors. Therefore, there were now manually entered data within that import. Did Turbotax try to do me a favor by not removing that one form? So far, all my experiments involving "remove import" with no manually entered data have not resulted in such errors. When I have time, I will try to reproduce manually changing import data.
