yeah...........if you are running parallel then you need to hook up charger to one battery, it will charge both
you didn't need the expense of a 3 bank...it's never good to hook up 2 charges to the same battery and in parallel that is what you are doing if you charge both batteries at the same time, each with it's own charger, unless you separate the batteries each time you charge them
if they are in series then you can hook up each battery