Pour pineapple on bottom of 9x13 inch baking dish. Add blueberries. Put 1/2 of sugar on pineapples and blueberries. Sprinkle cake mix over this. Sprinkle with pecans and other 1/2 sugar. Drizzle butter over.
Bake at 375 degrees for 30 minutes. Punch down to release juices. Then bake another 10-15 minutes.