Some of the signals may confuse you, but from what I can see, here's what I'd surmise:
At the offending RPM, the erratic action is causing multiple spark attempts in the coil. This is introducing an unprotected, out-of-phase reverse current in the engine block. This situation then is feeding back to the electronics in the Igniter, which dutifully (and properly, for all it knows) amplifies it and tries to trigger the coil with it. There is not enough energy left in the coil, because the short time between those little hash marks is not long enough for a coil to charge: thus the coil is being asked to dump at a time when it is actually in the "negative energy" state following the magnetic collapse.
That's why it makes those multi-fire like trigger pulses.
Cures:
1. Believe it or not, this can be caused by a bad plate in a battery. Try swapping with any other battery to see if it goes away (like maybe a car battery, with GOOD jumper connections to it, not clip-on cables).
2. Grounding issues: first, make dead sure the ground cable from the battery to the engine and frame is clean as a whistle, lightly oiled, where it contacts the frame and block. I have seen powdercoated frames cause similar problems: the paint blocks the contact between the ground cable's ring and the frame, so the current must pass through the bolt to the engine in one path, and there becomes a separate path somewhere else for the electronics. The electrical "distance" between the two makes for some resistance: this must instead be ZERO ohms for the crank trigger's ground reference. If it is not zero ohms, the crank trigger's ground voltage will momentarily spike downward when the coil discharges into the plug and block: this makes the hash marks you see on the 'scope. This is because the trigger is generating a couple of volts more than 0 volts, then the coil discharges into the block and the 0 volts momentarily becomes something less, like (-10) volts, eating up the trigger pulse.
Too much in-depth analysis:
When the coil discharges, it does it in several steps. The first rise in voltage polarizes the gap between the plug's electrodes and creates a sudden magnetic field: this points the way to the electrons that are trying to escape to the engine block. Once enough magnetic field builds up (about 3-4 microseconds), the electrons begin to jump the gap, and a plasma appears as some of them don't make it, and they give up their energy into building the plasma bridge (about 10 microseconds). This lowers the resistance across the gap, and the mob of angry electrons behind begin their rush to the ground side. Once enough of them cross the gap so that the magnetic field in the coil can fall off (about 200-500 microseconds, depending on the coil used), the magnetic field switches from "North" to "South", turning traitor and recalling some of the electrons: it actually reverses polarity at this point, and the voltage at the tip of the plug swings negative. This is the point where you see the first downward spike in your trigger trace, because the engine block has been pushed BELOW 0 volts, due to a poor ground circuit. Since the plasma bridge on the plug tip is still there, a bunch of electrons run home again (all at the speed of light, mind you), and when enough of them get there, the magnetic field reverses again, kicking them all out (like boomerang kids). This cycle repeats several times until the plasma falls apart at the plug tip, so you can see the effect in the ground side of your trigger: each downward spike on the trace is actually a field reversal of the coil during a single discharge.
...I don't want to get into the political analysis version, but in some ways, it does resemble Congress....
