pentejr: 2-2, 3-3, 4-4 and 6-6 are indeed 4 rolls.

However: 2-1, 1-2, 2-3, 3-2, 3-4, 4-3, 5-6, 6-5 are 8 rolls!!

remember non double rolls come up twice as often as double rolls.

In addition to playBunny's point that a double can be used well in your own home, whereas a 4-3 might not be so good without the split.