I will refer to these three images to aid the explanation this question.

Suppose I have two GameObjects in Unity 2D, both with Image components attached. Further suppose that one of the GameObjects overlaps the other in the scene space. This is illustrated in the first, leftmost image with a blue triangle above a red circle. The checkerboard background represents whatever else is in the scene, rendered partially underneath the red circle and blue triangle.

If I were to set the opacity of both of the GameObjects to 0.5 (that is, their Color is set to Color(1.0, 1.0, 1.0, 0.5)), something like the second, middle image would be the result. There is a purple image where you can see the red circle through the blue triangle.

I do not want this. I instead want to create the effect as seen in the third, rightmost image, it is if the two images were combined into a single image, and then their opacity was set to 0.5.

How can I do this?

I would also like to extend this to an arbitrary number of overlapping images, not just two.