Okay, so I tried this in the game, and I'm not sure if it's a glitch or intended or what.
Playing against Ambuscade and put Wrest the Mind on Reactive Plating. Someone hits Ambuscade, setting off Reactive Plating. I redirect the damage to Ambuscade. That also sets off the Reactive Plating to attack itself, which I again redirect to Ambuscade. Then Visionary does 3 damage (reduced to 2) to the plating, and 3 damage to herself.
Shouldn't she have done two instances of damage each to the plating and herself, since she redirected its damage twice?
Since you redirected twice I would agree Viz should have taken three damage twice and so the Reactive Plating two damage twice due to its DR
Crush your enemies, drive them before you, and laminate their women! - Guise, Prime Wardens #31