Project: Gorgon is a 3D fantasy MMORPG (massively-multiplayer online role-playing game) that features an immersive experience that allows the player to forge their own path through exploration and discovery. We won't be guiding you through a world on rails, and as a result there are many hidden secrets awaiting discovery. Project: Gorgon also features an ambitious skill based leveling system that bucks the current trend of pre-determined classes, thus allowing the player to combine skills in order to create a truly unique playing experience.
The Project: Gorgon development team is led by industry veteran Eric Heimburg. Eric has over a decade of experience working as a Senior and Lead Engineer, Developer, Designer and Producer on successful games such as Asheron’s Call 1 and 2, Star Trek Online and other successful Massively Multiplayer Online Games.
The effects are rolled separately, so you have two separate 5% chances to take damage when you use the ability. (It's rolled per ability use, not per target). I suspect what you're seeing is just one of the mods going off (the 128 one), but your indirect boost is applied, like this:
tbh that seems odd to me that indirect fire should increase backfire damage. indirect damage in this game generally is reserved for DoTs why would you all design it to increase this mods damage.
also I guess that explains why I am suddenly being killed now and then from backfire because I upgraded my indirect fire damage from 0% to +96%.