as suggested, don't use the C4D renderer for such basic stuff. Other than that simply slightly offset the two layers. Such glitches happen with pretty much any 3D renderer when layers are in the same position and the clipping calculations can't determine which is in front of the other.
What's the exact version of After Effects you're using? What are your system specifications (CPU, GPU, RAM, OS)? Also, is this issue repeatable on a new project? It could be related to the GPU. Please make sure that your GPU driver is updated to the latest.