No, it is the same account, since some were uploaded while others were not (no apparent pattern related to account access). PinkElephant, you might be correct about the monthly limit - I had not considered that, which means this was a user interface failure that I was not notified of that issue.
I've already switched to Dropbox scanning, which is actually more accurate anyway, so thanks to everyone who tried to solve this issue but I won't be testing any solutions from now on since I have switched. But thanks for taking the time!