Using the TurboTax online web-based editions only one tax return can be filed for each account and User ID.
To file another tax return you would need to create a new account with a new User ID.
You can prepare and e-file up to five federal returns with the state returns that go with them if you are using the desktop download software.
If you are using online TurboTax, you get one return per fee.
When you use Online TurboTax, you get one return per fee. Each return needs its own account and user ID. If you use the same account and user ID for a second return, you overwrite the first one and lose it forever.
https://turbotax.intuit.com/personal-taxes/online/