Every person I have ever seen that has driven an automatic with two feet has driven in the most dangerous of ways.
They would keep their foot on the brake while accelerating, which not only left their brake lights on giving others the impression that they were slowing down or getting ready to stop when they were not, but would also burn up their brakes vastly increasing the amount of brake pad replacements over the life of the car plus creating the risk of having the brake fluid boil leaving them with no brakes at all.
Also, using both feet doubles the chance that you will hit the wrong pedal in split-second emergency situations, or you will leave the gas pedal on while hitting the brake which will almost negate using the brake at all.