I'm not sure why there are two threads on this, but I'm happy to reiterate the gist of my post from the other thread where this was discussed for anyone who missed it. That's a Stadler KISS, specifically a lightly-photoshopped (into MBTA colors) rendering of the version being built for Caltrain. The California trains have the weird double sets of doors because they need to work with a.) California's standard 8" low platforms and b.) California HSR's unicorn 50" high platforms. Our high platforms are 48", and per the T's own RFI presentation the California KISS is not as-designed compatible with our platforms. The lower doors are irrelevant for our discussions because they can't be used at high-level platforms including the downtown terminals; without high-level doors compatible with our platforms the cars won't work at all. Presumably Stadler could modify the design for 48" platforms (I don't know if that'd include adding traps for the low platforms, or just keeping the low-level doors), but the word from on high is that it is not possible to just import California-spec KISSes because they're not compatible.
(And with respect to what would seem like a straightforward modification, there's the question of whether it's as straightforward as it seems like it should be, and, not necessarily relatedly, whether Stadler will do it, and do it at a price point to make these competitive with other options that are native-compatible with our platforms. Probably yes, but we'll have to wait and see.)