Viewports make for different lighting and 2-player menu controls

in Programming
Title. Why does my splitscreen lighting appear different than when the game is not split between two viewports?
And how do I make it so that both players can have a button focus of their own?
Comments
Which Godot version and rendering backend are you using (GLES3/GLES2)?
This is likely because the DirectionalLight is rendered twice. Check the remote scene tree to make sure you didn't instance lights more than once. If this isn't the case, then this may be a limitation of the rendering backend you're currently using.