I think this specific line from the Charge page on Bulbapedia is worth including just so anyone who sees the answer has the exact proof:
"Multiple instances of the Charge effect (using Charge multiple times while the user's Ability is Normalize, or using Charge followed by an activation of Electromorphosis or Wind Power) are not cumulative; the next Electric-type move will still only deal twice as much damage, and no instances of the effect will linger to be used on subsequent moves."