To be clear, I *like* the fact that the shades don't match, but I also like the look of mismatched guns aesthetically, but that's just personal cosmetic preference.
Realistically, however, while distinctly different in high-resolution, direct light photographs, the contrast between different gradients of tanodize is simply not sufficient to provide any kind of camouflaging/outline breaking properties, at a distance in the field, the anodized components would all more or less blend into a solid mass of a single color. This is a common mistake with many people who try to camouflage their rifles, but use a pattern that is too tight, or without enough contrast.
The simple fact is that tanodizing is a difficult process to maintain a consistent hue, and it's simply not worth the time and the effort to do so, and you would probably increase the cost simply due to the labor required, when the majority of users (military) who want a "non-black" finish are more concerned with the "non-black" specification, and not the "looks nice and uniform" department. Whether talking about Europe or the U.S., I would suspect that the tanodized/RAL8000 portion of the HK long gun market is almost insignificantly small relative to the number of military organizations simply interested in having something that's not black.
Bottom line is, as Geissele's DDC Disclaimer warns, if you're really interested in matching colors, you're far better off going with a coated finish of some sort, rather than trying to match tanodized parts.