Gas over/under oven/broilers were common. We discussed this in a thread on older stoves recently. A single gas burner is located between the parts providing heat from underneath for the oven and overhead for the broiler. In a gas stove this saves a lot of cost that would be needed for separate oven and broiler burners. The cost of the heating elements and wire in an electric oven is negligible in comparison so one chamber can have both underneath and overhead heat economically.