I defended DXO some time ago just because they publish their testing procedures first and then follow them when testing. But I think you will also admit, that when there is a place for some speculation it will always happen. When only one copy (even if production one) was tested, then someone always can ask questions:
1. Was it the only copy they had?
2. If no didn't they "carefully" selected one "special" copy for testing purposes?
3. If they publish tests of only one copy of gear, doesn't it open space for such speculations as above?
4. Do they have any interest in such behaviour if they are sponsored by one producent?
I don't say they do it like described above. But as far as there is a reason to speculate, people will ask questions and doubt.
Finally, DxOMark has no ties to or interests of any sort with camera or lens manufacturers, which means that we are completely independent from them.
edit - That and DxOMark has probably figured out that 99.9% of people posting comments have absolutely zero credibility or experience in testing sensors and/or lenses, and are just butt-hurt that the Camera/Lens that they purchased (or planned to purchase) didn't score as high as they believed it should. That and the posters just can't accept that their beloved product isn't the greatest thing since sliced sex on buttered buns.
Yes, but people believing in conspiracy say, that as far as Nikon uses their products and pays for commercial, then this absolute independence might be disturbed.
Yes, I believe that fanboys don't believe in independent tests. That's absolutely true. But in this case, anyway I don't find them as the only ones with groundbreaking discovery.
Anyway - I really don't know. I just mention what I'm aware of. I don't have nor had neither 70-200 2.8 mk1 nor mk2 so can't say.