Is double wrapping panels necessary?

I agree with the Knauf rep. I believe the GOM is possibly tighter than burlap and I had no problem in the past with burlap. Lately, I do double wrap with economy (cheap) landscape fabric, not for containment but for color bleed through. The landscape fabric is so thin is allows the color of the insulation to "bleed" through so doubling up is required for me to get a black panel. If you want to be super cautious, I suppose you could do one first wrap with the cheap, thin landscape fabric. My guess is you won't have adverse results either way.