Unless you had issues trying to file returns when Intuit was holding them for you that generated duplicates, the other potential explanation is that your system may have been hacked.
i am having the same issue. I had a bunch of efiles that I sent out Thursday night and Friday morning that remained in the “sent to irs” stage for 3 days until finally yesterday they all came back as rejected that returns with the SSN have already been filed. It has to be some kind of system glitch where duplicates were sent
Hi I'm Julie the ProSeries product manager.
I agree that this is highly unusual and would like to rule out that something didn't happen in our system causing the duplicate rejects. Please reach out to me directly at firstname.lastname@example.org at your earliest convenience. Thanks