Baking these two Ocean modifiers is pretty weird because there is the bug T80876 that causes a weird behavior.
You can bake both Ocean modifiers with the following steps:
- restart Blender and open the file
- enter two different Cache File Paths for each modifier, e.g.
//cache_ocean_2 so each modifier has its own cache and the data gets not overwritten. See screenshot 1 below. It's from the blend file where it is wrong!
- change the Grid Resolution to a different random value like
6. This change is just needed to repeat the step. Press the Bake button. Blender will bake now the images. But if you check them they all will be black. See screenshot 2 below.
- do it again. Change the Grid Resolution to the original value (
7). This will trigger the workaround for the bug and you can bake it again. Surprise! This time the images are backed correctly. See screenshot 3 below.
Of course, for some reason, this trick does not work for the second modifier right now in the current state. The baked images will always be black no matter how many times you try to bake them. Blender requires a restart. So let's do this...
- save a copy of the file (File > Save As...)
- restart Blender
- press the Bake Button of the second Ocean modifier. The Bake button will change its label to Delete. Congratulations! The images will be backed correctly.
Screenshot 1: Different Cache Paths. In the screenshot, they are accidentally the same. This doesn't work.
Screenshot 2: Black-Backed Images
Screenshot 3: Fine Backed Images