Click on a blue arrow of your selected or unselected (when you hover over the shape with your mouse) rectangular shape, so the draw.io shape picker opens. Choose the shape in the upper left corner to duplicate the original shape 1:1 (or use one of the most used shapes from the general shape library). The shape and its content is duplicated and connected with a connector in the direction of the arrow on which you clicked.
Now add another shape at the bottom of the rectangle, but this time we add the Double Circle shape from the Misc library. Drag and drop the shape on the bottom blue arrow of the rectangle to add and connect it at the same time.
Tip: By default, a connector is equipped with an arrow.