As XmasBaby0 points out, you should not do anything until the IRS accepts and processes your return. Multiple conflicting returns in the system creates confusion for everyone. The following applies to your question about what happens if the IRS accepts and processes your return without noticing the error.
In any case, make any additional payments due by April 15 to avoid penalties.
Welcome to the wonderful world of tax mistakes and amended returns!
You most likely will need to amend your return. Search in Turbo Tax for "Amended Return" and go from there. Once you have the amended return prepared, if there is any additional amount due, you can pay it at the IRS website before April 15.
I would recommend not immediately sending off the amended return. Your enthusiasm for tax filing is commendable, but it resulted in an incorrect tax filing. So... wait. See if you find any additional errors, or get any corrected forms in the mail. When you're sure that everything is correct, only then send in your amended return.
Note that your amended return will not be processed for a long, long time. In normal times, this was a few months. With Covid, it's probably not going to be looked at until October. If you are due an additional refund, then you have to wait. I think this is the IRS's way of punishing people for making mistakes.
