Usually if you switch over the state return, then go to exit, it will ask if you want to save or not, and you can choose NO, and the auto backup doesnt happen.

But Ive screwed myself too many times now by automatically hitting YES to save when I didnt want to, I always do a SAVE AS and add whatif to the end of the file name, uncheck the EF boxes and play with the copy, so I know the original is safe and sound.

You wont be able to import the PDF and get the whole return in there.  Sadly I think youre stuck re-doing it, unless your backup saved a copy of it after it was complete and hasnt overwritten it yet with the updated version.....I only backup once at the end of the day, so if I had the right version backed up last night and I screwed it up this morning, I can still grab that backup and restore it.