Yes, it is common. The dark stripes are harder, so they resist being worked or sanded and the light colored areas are softer so they work easier to sand or plane..
When I was fresh out of high school, I worked at a lumber co. that made bowling alley wood for AMF and Brunswick. There is maple in the area you run on and lay the ball down, then it becomes yellow pine until you get to the pin deck where it is again maple. In making these alley's, all wood that had any curl,birds-eye or figure to it's grain, was cut out and discarded. The reason being is that this grain in the wood would make the ball do strange things. We know what caused it, it was the hard and soft spots in the wood grain that made the ball follow the grain. It would be this way with any species of wood. Now I look back and think of all those beautiful muzzleloader stocks that were burned to make steam to run the power plant.
