Can you pack a punch twice?

No. You are allotted 2 weapons in every Level of Zombies. And up until recently (Treyarch patched the crap out of this), you were able to have every weapon in the box. But, with your 2 weapons, you can only Upgrade each weapon once. Each time you Upgrade a weapon, it costs you 5,000 points. The best weapon to Upgrade to get you far in Zombies (this is based on the Zombie map "Der Riese") is the Galil and the Hk-21 (also the RPK isn't so bad). If you are playing with some friends, it isn't a bad idea to upgrade the wonderwaffle either. Once everyone starts running out of ammo, start teleporting to get a Max Ammo and when you are in a pickle, the Wonderwaffle can take out 20-35 zombies at a time and you don't hardly have to aim with it. I hope I answered your question to the fullest. If you have any other questions, please don't hesitate to ask.

Semper Fi

You can upgrade as many weapons as you want in a single game but you can only have 2 weapons at once. Spiderbite from NextGenTactics pack a punched 15 weapons in a single game. But you can't upgrade an upgraded weapon.