Carry the original. If you carry a copy it probably will not be considered a legal document AND you WILL be spending a lot of quality time with your local law enforcement when you could have been left to go about your business.
I have never worried about carrying the original. I keep it in an ID wallet with my DL and its convenient, and when handing to an LEO they appreciate the fact that they don't have to ask for it since it shows you have nothing to hide.
Better to be safe than sorry...
If it weren't for guns, we would still be British.
A quiet man is a thinking man. A quiet woman is usually mad.