Hello EnuwEpoch,
The node which grants the greater puncture - “Cadence of Death” states “Every third puncture deals more damage (multiplicative with other modifiers) and in a larger area” when you hover over it. This is the greater puncture in question, which the following reliant node “mutilate” also causes it to consume all bleed stacks and deal damage instantly.
The bleed damage does not double dip. All of your stats were applied to the initial bleed damage when it was first applied. It takes the stacks of bleed, adds up all the damage and deals it “instantly”, basically making the bleeds run through their timer in an instant. Like how Taste of Blood causes bleeds to speed up, this node does the same, just speeds up all stacks to an ‘instant’, they still remain the original bleeds that were applied.