There is a lot of speculation going on about who the second killer is, but the most important question is whether or not the other killer is a serial killer or is aligned with town. The kill targets say "aligned with town", but we can't at all be certain yet.
I would say that it is unlikely that we have two town vigilantes, but it is possible that we may have a deputy vigilante or universal deputy who inherited Dysk Soldier's powers. Power roles do seem a little strong in this game, based on Swamped's flip.
On the other hand, a serial killer successfully building town cred would be a dangerous thing.