Molten Blast dual wield does not double extra projectiles from Run and Gun passive

Title pretty much sums up the bug (or unintuative skill interaction).

Can be tested simply by equiping two maces and using molten blast having the Run And Gun passive allocated.

when attacking (while in running animation - because the moving animation of the skill does not itself count as moving for some odd reason) You would see 2 projectiles when Run and Gun does not trigger.
However, when it does trigger, two additional projectiles flies out, so 4 in total.
I would expect dual wielding Molten Blast that it would throw out 6 projectiles (3 base proj and doubled because of dual wield).