I tried your numbers on the wyeast calculators and the numbers were a little different.
if you do 2 packs in 2 liters you will end up with ~ 24mil cells/ml
if you do 2 packs in 1 liter you will end up with ~ 18mil cells/ml
wyeast recommends "A general rule of thumb is to pitch one million cells per milliliter per degree plato."
you are at ~ 22 plato so you would want about 22 mil cells/ml
if your using a stir plate you can get to 22 mil cells using 1.5 liters and 2 smack packs.
I think Mr Malty uses a default of 18mil cells which is why it said 1 liter.
You are probably better off making 2 liters and pitching when its at high krausen. As far as competition they are going to chew through everything in that starter pretty quick