Theory. With two people dying each night, there must be a second killing role. Two roles dealing with bombs seems like overkill if we only have one or two normal bombs.

However, Apollo being a Serial-Killer with bomb flavor (terrorist? ) could explain all of this. Perhaps it's some setup where Hera was suppose to find the terrorist. This also explains the addition of the Hurt Locker. Something for the mafia to combat the Serial-Bomber with.