That's a problem, seems like a ID Theft issue which was very common this year, if the same error comes over and over, consult online help with a tax professional, you may have to paper file and submit ID theft form.
Did you submit your information through one of the non-filer applications in order to get your stimulus payment? There are non-filer options either through TurboTax or the IRS.
If so, when using the non-filer system, your information is processed by the IRS as an original filed return.
If not, then you may have a more serious identity theft issue to address.
See the following TurboTax articles for some additional advice about your situation:
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It could also be if you signed up on the IRS non-filer tool to give the IRS your Direct Deposit Info for the Stimulus Check. If you did then see
According to what I have read on the Web, the most common cause of this problem is some discrepancy in a birthdate, AGI or other identifying information. Do re-check this before worrying about identity theft.
When this same thing happened to me several years ago, it was due to someone stealing our identity and filing a tax return using our information. I suggest contacting the IRS as soon as possible to see if this is the case.