How to not let drop shadows darken each other out

Question

I'm looking for a technique to avoid drop shadows on individual elements darkening each other out (multiplying the effect of the drop shadow).

This is an image showing the undesired effect I'm talking about (also enlarged at the bottom of the image). I want the drop shadow on the white surface to be the same whether the shadow is from one of the elements or both "on top of each other".

Anyone know how to achieve this fairly easily?

Answer 1

Combine both objects into the same layer or smart object and apply the shadow to that instead.

Update: To keep the shadow from the top object on the bottom, in addition to the steps above, duplicate the top object with shadow, and put into a layergroup. Now apply the lower object as a layer mask to that layer group (set that area white on black background in layer mask). This will limit the shadow and object to only the areas above the lower object.

Answer 2

EDIT: Ugh, just posted this answer and then realized you were in Photoshop and not Illustrator. I'll leave it up because Illustrator is good for this sort of thing too, and the same principle can certainly be applied in Photoshop.

Here's what I came up with:

1. Two rectangles with drop shadows:
   

2: Duplicate the two rectangles and then do Pathfinder > Merge or do the layer/smart object thing that John suggested:

3: Take the top rectangle, place over top of your new merged path, and then draw a rectangle over the drop shadow part that goes over the rectangle:

4: Use the new rectangle as a clipping mask: