I should also have mentioned that if your main comp doesn’t have a light layer then things are okay.
Therefore, you may want to have a 3rd comp – a final comp that doesn’t have any camera or lights where these two 3D comps can reside – ensure that you have Collapsed Transformations switched on for the nested 3D comps. The downside is that I really don’t know how lights from the two comps are going to react to each other.
I’m not on an AE-capable PC right now, so you’ll have to run quick tests to see if it’s a viable option.
Cheers
Roland Kahlenberg
https://www.broadcastGEMs.com – Adobe After Effects project files
https://www.myspace.com/rorkrgbspace