Could you try to use one rendertarget for the server and a different one for the client (via e.g. IsServer set them to use different render targets)? Cause since you’re not running two separate instances (like connecting two computers), it may be that they’re both writing to the exact same render target texture and then you just display the same render target twice (once on server and once on client).
At least that’s what happened when I just tried it with the same render target.