Being in a waterproof metal can does not stop metal from sweating on the inside of can causing moister/condensation to form on inside of a waterproof can.
Depending on your weather or where you store can, Metal sweats and can cause mold to grow from the dampness from sweating. As long as your not having a problem that's great.
Not sure what your plastic netting is but sounds like it wouldn't be waterproof being netting. Sounds more like as you stated its for reinforcement rather than waterproof. Layers of paper will just transfer moister.
I agree with others on metal cans but probably good to leave feed in bag in metal can, not just dumping it in. Depending on your weather or where you store can, Metal sweats and can cause mold to grow from the dampness from sweating. I just line my cans with plastic bag and or leave feed in...