Is Repetitiveness Always Intentional?

As we've been discussing originality, I've noticed that we've taken a rather accusatory tone when talking about art that seemingly fails to be original. We talk a lot about artists (filmmakers, writers, musicians, etc.) as though they always intend to be unoriginal, like they are knowingly and purposefully ripping off someone else's work. According the Frankfurt theory about media, this is precisely what artists are doing. They saw it all as a giant scheme to keep reproducing the same things just to placate audiences and rake in more money.
However, I believe that many of these artists' intentions are far more innocent. I can personally think of many times throughout my life that I proudly came up with what I thought were completely original ideas for stories. It was only much later that I'd be reading one of my stories and realize how obviously similar the plot was to other, more famous pieces.
I've learned from myself that even when you suspect an author or director of blatantly recycling another's ideas, they may have just been innocently oblivious to what they were doing. I used to be incredibly angry with Christopher Paolini, author of the Inheritance Cycle (aka the Eragon series), because I firmly believed he had intentionally stolen J.R.R. Tolkien's Lord of the Rings world and made it his own for personal gain. Now I see that he was just a fifteen-year-old boy who probably just failed to see the countless parallels between his work and Tolkien's.
So, all of this reminded me of a film I saw two years ago at the Sundance Film Festival called Stoker. From the very start, I was noticing a lot of Hitchcockian influence in this sinister, slow-burning film. By the end, it was so very obviously like Alfred Hitchcock's film Shadow of a Doubt that I thought the director, Park Chan-Wook, had made Stoker as a very intentional, modern nod to the 1943 film. I was surprised to find out in the Q and A afterwards that he hadn't even noticed the similarities until later on.
Here's a trailer for Stoker:

Here's a trailer for Shadow of a Doubt:

As you can see, there are several parallels between these two films. In both, the main girl's mysterious uncle comes to stay with the family and soon befriends his niece. The girl develops a sort of infatuation for Uncle Charlie, and eventually discovers that he has a thing for murdering people. 

(Here is a picture I took of Park Chan-Wook and the cast at the premiere of Stoker.)

It seems as though Park Chan-Wook specifically intended to pay homage to Shadow of a Doubt, but he insisted in the Q and A that, while Hitchcock did inspire him to get into the film business, he didn't mean for there to be any connection between his film and Hitchcock's. He did admit, "In many ways, although I tried not to consciously think about it, I must have been invariably influenced by Hitchcock."

Does that mean Chan-Wook is in the wrong? Does it cheapen Stoker, or make it any less interesting? I don't think so.