Hi,
Assuming I have to use RenderTarget, the best I have so far is to use a single image to display both cameras with 2 render targets.
In the material assigned to my image (UI) I have 2 render targets (as parameters), and each one is displayed only when the pixel is closest to its associated character (I use some 2d coordinates of where each character is as parameters).
to fix the lighting difference you gotta enable lumen in the scene capture seperately
About lighting, I disabled Lumen in my project and it has some differences in results… 