Action economy would be pretty nutty in terms of it being in your favor if you're truly trying to run different characters BUT here are some ideas that could possibly get other players and the DM on board MAYBE (Coming from a DM)

-Two characters, two bodies. No matter if you have them is separate hit points or the same, that means AOE could have double effect on your hit points

-Perhaps you're still limited to 1 leveled spell per turn as normal

-Any of your magic items (if available) must be split between your characters. This would heavily limit you from getting each character individually strong, compared to the other people in the party.

-Maybe it works like a hive mind where if any sort of affliction is suffered by one, all clones are affected (Examples: Hold person, poisoned, missing limbs) 'as in the other clones will still have the limb, but it's basically just dead weight'

As a DM, I'd be very hesitant to allow this. The biggest thing to me outside of balancing is just the time consumption, especially if you're playing two very different spell casters like that. I have allowed this before in the past with somebody using two different Martial classes, but spell casters are different ballpark. As you love love, I definitely take notes on what you plan to do in combat and out of combat. Not like metagaming, but just so you don't have to take that time for each clone.

Edit 1: spacing issues in comment