Another good thing about these 'original' keys, is that the cut of them is very often better than that done in a hardware store, resulting in smoother action in use.
I always tell customers to save at least one of the original keys that came with a lock set to make copies from in the future. Put this key to the side and do not use it. I am sure almost everyone has had a key that is a third or further generation cut from the original, and though still may work, often has to be wiggled around to do so. Not only are there small errors made when cutting some times, but keys wear, and this wear is then carried on to successive key cuts.