I have never heard anyone wanting anything other than a copy of the C&R for any transaction. Several years ago, I heard of some dealers wanting a signed copy mailed to them; that is an original signed copy.
Today, most I have dealt with will accept a signed e-copy. Some individual sellers will in some instances expect you to comply with your states laws and you will see clauses saying it is your responsibility to do so.
Most honest dealers are familiar with state laws and will expect you to comply: IE, Illinois FOID card must accompany C&R.