How can I combine two displacement without the face normal changes of one screwing up the other? I'm looking to apply an animated displacement to a surface which has already been displaced with a cloud texture (creating an organic lumpy base surface).

It should look like this...



...applied to this...



...but instead it looks like this:



Source files here and here.

The problem is that the normals changed by the first displacement completely screw up the second displacement (I think).

Does anybody know how I can achieve the double displacement of my dreams? I think I need to find a way to redirect the surface normals after the first displacement, but I'm open to any suggestions from you wonderful people.
I was able to achieve the effect I desired by using the Warp modifier after a displace modifier to provide initial organic displacement. Performance in Blender was much slower, but as I'm baking the results this was a non-issue.