It's a good think costco doesn't sell hops, or you would really have a problem!True. Honey, I picked up 400 pounds of MOTUEKA!
A question: are you guys vac-sealing your hops? I picked up an El Cheapo sealer on Amazon and it's been fantastic so far. It creates a very good seal and the hop bags are as hard as a rock. My hops are staying much fresher much longer.
One thing I learned early on is to not cheap out on bags. Cheap bags can let air in through the surface of the bag.
I only buy the bags that are recommended by the manufacturer of the sealer. That said, if you don't make sure that the bag is completely sealed on both ends, they will leak in air (I occasionally run them through twice, especially on the bottom end). Doesn't happen to me very often, but every once in a while I have to re-seal a bag that has leaked.
The idea of double bagging is a a good one but if you have good quality bags, you might not need to spend the extra time and money on bag material