In a food processor, puree strawberries with 1 T. sugar. Transfer to a small bowl. In processor, puree blueberries with 1 T. sugar. In another small bowl, whisk together yogurt and 2 T. sugar. Pour the 3 mixtures, alternating, into ten 3-oz. ice-pop molds, making 3 to 5 layers each. With a skewer or think-bladed knife, swirl mixtures together in an up-and-down motion. Insert ice-pop sticks and freeze until solid, 2 1/2 to 3 hours (or up to 1 week).