I am often asked by people at a conference or event how they can get a copy of a photo. They see me shooting and pose for my camera and then want a copy of the picture. I could make some extra dough by selling such copies to individuals. That, however, in my opinion, would be double dipping. My client is paying me to make and develop and deliver the images to that specific person and business. Therefore, I tell people asking about copies to just get in touch with the person in charge of the conference or event.
In some cases a person might want "all copies" of an image but I'm afraid that, once an image is made, it never really goes away. More on that in a subsequent post.