Can you show me an image where 2 soldiers, both wearing fatigues, have an identical camouflage pattern? Every image I find on Google Images has a distinct pattern per soldier.
It isn't a per-soldier thing. It's just pieces of fabric that are all cut differently. They aren't out there making sure one person has a specific pattern that matches every single one of their uniforms, and doesn't match someone else's.
I get the line of thinking, and I tend to agree that if they really wanted to, they could figure out a way to match the pattern of a uniform to the person if the person had published a picture of themselves wearing the article on something like Facebook.
But that's a big if. When I was in the military, I think I posted like one picture of me in camo and the resolution was so low that you probably didn't have enough detail to come to any conclusions.
The US has about 24K soldiers in Korea. That's not that many. Presumably they stand at attention every so often anyways. So photograph them all standing at attention and match the camo.