Peppers cross breed fairly easily, so yeah, I say if they grew close to each other, they could have crossbred. This is why seed sellers have to be careful to make sure their plants are isolated so you don't get some crazy hybrid.
They are both Capsicum chinense and can crossbreed (hybridize). However, the hybrid phenotype will only be evident in the F1 plants (plants grown from the seeds of the hybridized fruit). Crossbreeding (cross pollination) does not show up in the initial fruit. I'm not sure if the fruit in your picture is from the plants growing up next to each other or from plants grown from the seed of the parent plants.
Joe Wayne Willis - Thanks for the education. The chilli you see here is possibly from a direct cross pollination. I am stumped by the "tails" on these Chocolate Fatallis though. I imagined this tail was a Reaper trait. But, if i understand you correctly, i would not see this with the initial cross pollination.
New to your site and catching up with past posts. Didn't realize these plants would/could cross. I've had to manually pollinate my three plants: a ghost pepper, a reaper, and a chocolate scorpion. I used the same Q-tip each time i did this process. Might have some very interesting results!