That like saying there are only so many ways to make a car...you know four wheels..engine..hood. It's all the same. Or a phone...speaker, mic, screen..it's all the same.
I can give you 10 headers from 10 different brands, and besides being bent pipe, none of them look similar (assuming you have some basic cognitive ability). There are difference not only in the bends, but in overall length. So when one header is the exact mirror image of another, plus works with that companies mid pipes, yes it is a copied design.
Yes, there are two headers in this picture.....
If designing a header was so easy, and R&D is something with no cost and value..why don't they design their own stuff? Would seem like the right way to build business to me? Certainly would shut me up. But I bet it is hard to R&D prototypes when all your machinery is owned by a contract manufacturer overeas.
The thing is, most people forget this stuff is designed using very expensive equipment like CMM arms that map the engine bay. They are also bent on CNC benders. Both of these require damn near engineers to run and program. That is why when you buy a header now, it fits, and has a life time warranty.
Also forgotten is 15 years ago and earlier, installing headers was a terrible experiance. Sure you could get some $200 Hooker or whatever headers at Pep Boys or Track Auto. But they were mild steal, and made with zero consistancy because nothing was made on computer controlled equipment. It was the norm to have to beat headers to get them to fittest, or cut your car. 5 years later when the header rusted away, you did the same thing over. And there was no complaining on a forum about a header rubbing..you just dealt with it...it is part of the game.
Because of that, the whole value in a Kooks header, or any of the premium brands is their fit. The fact that they spent 400 hours engineering a header using high dollar equipment. The fact that they are made on computer controlled CNC benders, and welded in high dollar jigs so that every header is the same. The fact that the person who makes them actually knows what they are welding, and the support rep on the phone likely has first hand experiance with your car are part of the value.
Again...my point is..if it was easy, and it was just bent pipe..then I see no reason to ever steal anyones design.