Original Vs Copy

I've brought this issue up before, but it's worth repeating.  In photography, what's the difference between the original and a copy?  In a medium that's designed to be endlessly reproduce-able, is it even a valid question?

I picked up these three postcards from an EBay dealer.  It was a couple of years ago, and I can't remember all the details, but I do remember that they were advertised as vintage postcards.  Imagine my disappointment when I opened the envelope only to discover that they were modern reproductions.  But then again, postcards often had decades long production runs?  Just because the production method had changed from the classic linen type, well, they're still  images that date back to the first several decades of the twentieth century.  A postcard collector would feel cheated, but my main interest was the image itself.  And since they look the same as an actual vintage card,  what's the difference?

During the great depression, the FSA, The Farm Security Administration, hired some of the best American photographers of the era to travel around the country and document what was happening on farms and in small, rural towns.  The negatives were shipped back to the FSA, and today are housed in The Library of Congress.  Sometimes the photographers were able to print their own negatives, sometimes they were printed by unknown government employees in Washington.  As I've mentioned in many a post, I spent years working in darkrooms.  Give me the right equipment, and the right paper, and I can make prints almost indistinguishable from the first prints made in the 1930s.  Printers are still making prints from original  FSA negatives, or first or second generation copy negatives.  Are they copies rather than originals because those new prints weren't made at the time the negative was exposed?  If so, what's the time frame for an original print?

I don't want to go into too many details.  A photographer, far better known for his work in other media, was a client at one of my former employers.  He was what we called a button pusher.  He had money to buy lots of film, and he took lots of pictures, almost at random.  He'd send in his film, I'd process it and make proof sheets.  Every so often, I'd get a request for a print from one of his negatives.  So, I'd make him a print.  The thing is, I was the one who made the decision on crop, contrast, density, dodging and burning.  I'd send him an 8x10 print on resin coated paper, he'd okay it, (I can't remember him ever asking for something different.) and then I'd make another print on fiber base paper.  I know for a fact that some of the prints I made for him have ended up in both private and museum collections.  If another printer were to match my originals, what is it?  A copy?  What if another printer made a print from one of those negatives with a different crop, hotter, flatter, lighter?  Then what is it?  A whole new work?  And what of the photographer himself?  Since he's letting other people  make editorial choices, are the photos made from his camera original negatives wholly his work?  Copyright law would say yes, but I'm not so sure.

It's easy with a painting.  If another artist comes along and makes a copy, it's just a copy.  But with a photograph, it's not so straight forward.