In the unity of why most of the eyes are part of the black? what is the benefit? can I remove it？

looks like you're using an old dev kit and old software, what are you working with?

I would like to look at the realization of Gear VR split screen principle, I saw an article, look it   http://paulbourke.net/stereographics/Unitystereo/   what is the difference between them?

again, what unity version are you using, what HMD are you using?