In a small bowl, toss blueberries with 1 tablespoon of granulated sugar; set aside. In another small bowl, toss strawberries with remaining tablespoon of granulated sugar; set aside.
In a third small bowl, stir together oats, brown sugar and butter. Spread mixture in a single layer on a sheet pan; bake, stirring occasionally, until lightly browned, about 15 minutes.
Spread blueberries and strawberries in an 8 x 8-inch glass dish, alternating to create stripes. (Or prepare in individual serving bowls like we did here.) Sprinkle with oat topping, decorate with whipped topping and serve. Yields 8 servings.