The last thing you want to do, is to confuse the guy behind you during a hard, panic braking situation. Those few seconds they might need to realize that a "double sequential" on your tail lights means you are braking, might be all it takes to smash your tail lights into small pieces of plastic.
If I remember right, one of those will make the brake lights sequential too. I'd go for the other one. When I hit the brakes, I want the person behind me to know I hit the brakes. I want my brake lights to go from 'all off' to 'all on' instantly.