It depends. If you already filed a return and then sent another the IRS will reject the second tax return due to the same social security number (SSN). They will only accept it once on a tax return.
Once the return rejects you can clear the return of all your input data. The link below will show you how to clear and start over.
If this was the same sign in as your original return, you may have lost that original data. You can retrieve it by using the IRS Transcript when it's available, if your original return has been accepted.
If you have additional questions or need more assistance please add any comments and we can help.