Cool if it’s true- I’d like to be able to do that.
Wow… I can’t even imagine doing that.
I’ve heard of people doing it before.
I can do it, but I can only do it if the subjects are about something that I know well and if I don’t worry about it. It’s like dancing, because as soon as you start thinking about it you can’t do it well.
When I was young, I used to play the piano while singing an entirely different song. (Drove my mother nuts). Richard Feynman also practiced doing different things simultaneously. The idea was that you could use different parts of your brain simultaneously.
It does make one speculate on the nature of “One’s True Selfâ€
I have enough trouble getting my brain to do one thing at a time. 
Come to think of it, there have been times I’ve typed/written something perfectly while listening with full comprehension to something completely unrelated. I think part of it is not realizing you can’t do it. I used to reliably be able to hit a milk jug with a 4" K frame Smith out past 150 yards - until I “learned” that gun can’t do that.