Puree strawberries in a food processor. Transfer to a small bowl. Puree blueberries in a food processor. Alternate layers of strawberries, blueberries and yogurt into ten 3-ounce popsicle molds (about 3 to 5 layers in each). With a skewer or knife, swirl mixtures together. Insert popsicle sticks and freeze until solid, 2 1/2 to 3 hours. Store up to one week.