Preheat the oven to 375 degrees.
Drain one of the cans of peaches, reserving the syrup. Empty the peaches into a lightly greased 13 x 9 - inch baking pan. Empty the entire contents of the second can of peaches - including the syrup - into the pan. Spread the peaches out evenly across the bottom of the pan. Sprinkle the cinnamon sugar mixture over the top of the peaches.
Sprinkle the cake mix on top of the peaches trying to make sure to evenly cover the peaches.
Cut the butter into thin slices - about a dozen or so - and arrange them across the top of the dry cake mix. Pour the reserved peach syrup over the top of the butter & cake mix. Sprinkle everything with the brown sugar.
Bake in the preheated oven for 45 - 55 minutes or until the crust is no longer soft & has become golden brown. Remove from the oven & allow to cool slightly before glazing.