Filing a second return would create a much bigger problem. You should amend your original return
after it is accepted by IRS and add the interest income.Go back into Turbo Tax and you will see at the bottom left of the screen "Need to amend a filed return". Then go to Personal Income, I'll choose what I want to work on, scroll down to Interest and Dividends and you'll see interest on F-1099-INT, then add your F-1099-INT. You will need to print and mail the amendment (with your payment) as it can't be e-filed. If it's a small amount you could just let IRS catch it and bill you (or you could send IRS the additional amount of taxes you know you will owe before they catch it.
