After you file

Unless you used a mailing service with tracking there is not a way to know for sure that the IRS has your mailed return until you see something on the IRS refund site - -   so it is a judgement call for you.  TurboTax cannot find out if the IRS has your return.  Putting two returns into the system at the same time can lead to confusion and even more delay.    

There are millions of people who are waiting for the backlogged IRS to process their returns.   See below:

From this IRS website - https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue

 As of June 23, 2021, we had 17.5 million unprocessed individual returns in the pipeline. Unprocessed returns include tax year 2020 returns such as those requiring correction to the Recovery Rebate Credit amount or validation of 2019 income used to figure the Earned Income Tax Credit (EITC) and Additional Child Tax Credit (ACTC). This work does not require us to correspond with taxpayers but does require special handling by an IRS employee so, in these instances, it is taking the IRS more than 21 days to issue any related refund. If, as a result, a correction is made to any RRC, EITC or ACTC claimed on the return, the IRS will send taxpayers an explanation. Taxpayers are encouraged to continue to check Where’s My Refund? for their personalized refund status and can review Tax Season Refund Frequently Asked Questions.

How long you may have to wait: The IRS understands the importance of timely processing of tax returns and refund issuance. We have processed all error free returns received prior to 2021, and continue to work the returns that need to be manually reviewed due to errors.  We are rerouting tax returns and taxpayer correspondence from locations that are behind to locations where more staff is available, and we are taking other actions to minimize any delays. Tax returns are opened and processed in the order received. As the return is processed, it may be delayed because it has a mistake including errors concerning the Recovery Rebate Credit, is missing information, or there is suspected identity theft or fraud. If we can fix it without contacting you, we will. If we need more information or need you to verify that it was you who sent the tax return, we will write you a letter. The resolution of these issues depends on how quickly and accurately you respond, and the ability of IRS staff trained and working under social distancing requirements to complete the processing of your return.

What you should do: If you filed electronically and received an acknowledgement, you do not need to take any further action other than promptly responding to any requests for information. If you filed on paper, check Where’s my refund? If it tells you we have received your return or are processing or reviewing it, we are processing your return, but it may be under review. We’re working hard to get through the backlog. Please don’t file a second tax return or contact the IRS about the status of your return.