It may be a bandaid, but I had the same scenario and put a balance tube in and now they are both nice and clean (left side set 1/4 turn less than right, based on decel popping).
I want to ask- when you pull your plugs, what was the last throttle position? What I'm getting at is if you ran 10 miles at 1/4 throttle on suburban neighborhood roads to get home and then pulled the plugs, you're looking at your mix at a specific part of the fuel delivery system (refer back to Pat's post on plug chops).
