Again, in his defense, the reason he wants a backup is because he's been beaten down by the Gov'mnt so many times. That said, after 15 years in the business, I know what dealers do it right and what ones are 'overly cautious' to put it kindly. I have a few 'dealers' on my list that are sketchy in one way or another. One demanded that I fill out TWO 4473's for the purchase of a handful of AR-15 receivers. The form clearly stated that you MUST do a continuation form, not a separate 4473, if the quantity exceeded the number of places on the form. He had no clue what that meant or how to do it. He also demanded that the 4473 say, "rifle" when they were not rifles, they were component receivers that I intended to build as pistols. He wanted to avoid doing a multiple sales form. Another dealer had carbon paper and wanted a 'copy' of the 4473 to send to 'corporate' so I would have signed TWO 4473's. I ignored him and filled out one. I told him he'd have to photocopy it and I would only sign once. Ended up leaving that one on the counter and walking out of the store.
To answer your question, though, good luck calling the ATF or finding anybody who cares or will answer a question.