bet pays 2 to 1 on both the 2 and 12, then the house edge is 5.56%.
if the field bet pays 2 to 1 on the 2 and 3 to 1 on the 12, then the house edge is 2.78%.
if the field bet pays 3 to 1 on the 2 and 2 to 1 on the 12, then the house edge is 2.78%.
if the field bet pays 3 to 1 on both the 2 and 12, then the house edge is 0.00%. 