The head shape of black pastels and cinnamons is simply different, and after you get used to that, it's not that hard to spot. There's a nice profile head shot on number 2 that shows the slender snout of a black pastel, and also the nice dark head color associated wtih it.
The markings on that snake bear it out, as well.

Folks who are confused as to the number of snakes need to look more carefully.

Also the first photo of snake #2 shows one of the side blotches with a dark shadow ring above it, typical of a black pastel. It's REALLY hard to see, because the photos are dark, blurry, and from a horrible angle. I didn't see that until I looked a lot closer just now, because the head shape and color was a dead giveaway.

#2 is a black pastel, and no mistake about it.