If you are going to make a photocopy of an original Scottish birth record OR make a digital copy double check the back side. Oftentimes the christening/baptism date was written on the back (mine being an example). Also check information that might have been added onto the certificate at a later date. I have a number of birth certificates where the christening dates have been written in, and signed by the minister.
I have copies of a number of OPR pages that I am revisiting. I originally got them because a specific family member was recorded on each page. One page I am currently "re-visiting" has two or three other people on it that are family but I did not know that at the time the copy was made.
I also have both copies of the Certificate of Proclamation of Banns that were posted for my maternal grandparents. The marriage date was written in after the event on both copies by the minister. One of the pieces of paperwork is "suitable for framing" :)