A 10 5 3 ♣ A 4 2.
Using Rule of 20 with only 12HCP and 4/3/3/3 distribution you cannot open. OR can you?
Before we go on, look at how many tricks you can make in both hands. There are various ways to play these combinations, but for the purpose of the exercise we will play for split honours.
With Hand A
There are only 2 tricks to take in Spades irrespective where the king lies.
There are 3 tricks to take in Hearts UNLESS the suit breaks 4/2, in which case there may only be 2
There are 2 tricks to take in Diamonds if honours are split.
There is only 1 Trick in clubs if the King is sitting wrong
With Hand B
There are 3 or 4 tricks to take in Spades, depending on position of the King
There are always 3 tricks to take in Hearts, due to the high intermediate cards.
There are 3 tricks in Diamonds with split honours
There are 2 tricks in Clubs, again with split honours.
The likelihood is with hand A, the hands will make 8 tricks in NT.
With Hand B the hands will make 11 tricks in NT.
Yet this is with the same HCP of 12 points. Therefore as you can see, it is VITAL that you add points for 10,9 combinations when they are headed by a higher honour. I would count these combinations as a full extra point. Hand B now is worth 12 plus 1 extra point for each of the 10/9 combinations making a total of 15.