Like my title says, 2 chargers are definitely needed to have the GT1 charge withing 5 hours instead of 10 hours with a single charger.
Ive had my GT1 for a month now and definitely see the need for a second charger.
So if you can ,solve the longer charging time by getting a second charger. It definitely helps. You can plug 1 at a time and you wont get any errors vs other scooters that seem to require you to plug two chargers at the same time before plugging them into the wall.