Still working on getting the 2nd charger installed. I have a 200A panel that is at capacity with a 240/50A spa and 240/50A charger (the first one installed 5 years ago). I looked into a 400A upgrade, but we have to move a wall to make room, so that's a no go.
Electrician is going to run a dedicated line back to the panel for the 2nd charger to make it future proof incase we ever do a panel upgrade. An alternative is to put a sub panel in the garage and feed both chargers off of that.
First charger is a 50A circuit with car limited to 40A (upgraded gen 1 to gen 3 already). With 2 chargers sharing 50A, each will be limited to 20A charging current until the smart sharing firmware comes along. This works out fine as we charge starting at 11pm when we have our super cheap EV rates (6.3 cents/kwh) and car is done charging in 4 hours. Even if it takes 8 with 'dumb' sharing, we are still good.