This appears to be a classic example of PAL-NTSC ghosting derived from improper conversion. The Kino - Region 1- NTSC edition uses the same PAL master from the German Transit-Universum (Friedrich Wilhelm Murnau Stiftung), BUT they did not pre-convert to NTSC for their standards' (Region 1) audience. I imagine it was done for monetary reasons as it was far less expensive than paying for the conversion. Unfortunately, the result is that those viewing the Kino edition DVD will see all the prevalent flaws that this common transference practice produces - 'ghosting' in motion sequences (see below), blurriness, artifacts and in this case some dis-colorization. I find the Kino has a blueish tinge to the more grey sequences. For purists, another huge difference is that the Kino have pre-translated the title cards from their original German into English. This is totally out-of-place or anyone respecting this films origins. The Eureka intertitles can be optionally subtitled.
The Eureka edition (an exact duplicate of the Transit German DVD, and marginally less expensive) is on 2 discs - pushing the The Metropolis Case A Making Of Documentary to its own 2nd DVD thereby not impinging on the data storage/transfer of the feature film. The Eureka menus give an initial offering of 5 language choices.

Side-by-side comparison shows how much better the Eureka DVD looks, with incredible greyscale, detail, definition and without any of the visible artifacts on the Kino.