Still no answer to the "The submission is a duplicate of one previously received??

I haven't had any at all this entire year, so its not a system issue.

Are these extensions for new clients whose previous tax pro might have sent in extensions for them already?

That seems like an awful lot of potential ID theft issues.

Is it the same as this?

https://accountants.intuit.com/community/proseries-tax-discussions/discussion/submission-is-a-duplicate-of-one-that-was-previously-received/00/357365

@Bennett2014 Thank you for being part of this Community and for posting your questions and concerns. We truly appreciate you being here. If you haven’t already, please reach out to ProSeries Support for assistance, as they can best help with your specific situation.

One possible explanation: I've often had ProSeries lose track of an e-file acknowledgment and revert the status back to a pre-E-file status. If that happens, then attempting e-filing again would produce the result you're seeing.

The fix is to select the client in the EF Center, then in the menu go to E-file > Electronic Filing > Update acknowledgment status.

If it doesn't update to E-File Complete, then this isn't the right answer for your situation.