Thank you so much for your reply, Jay D. All these years I had no idea one could manually edit the IRS forms directly in TurboTax ... I wish Intuit would make that clear in the application!
Unfortunately, I needed to recreate my entire tax return in order to fix the problem within the TurboTax "questionnaire" (this got rid of the duplicate IRS worksheet it had created the first time). BUT I will remember this option in future years' returns.
