C29 Are You Playing with Me

The original owner of the body didn't finish his sentence, but Su Mu had already guessed what he was going to say next.

There is no need to distinguish between us, because you are me and I am you.

What did that mean?

You are me. I am you?

Had the original Su Mu already merged with him, or had he always been in this body?

And why did the original Su Mu look exactly like him