Good catch, Rowuk. That is most likely what his question was.
I remember as a beginner seeing two voices on a part and asking how do I play two different notes at the same time. Just one at a time, I was told.
As I improved, I found I WAS able to practically make two notes come out at the same time, both wrong ones. SPLEEAGH! If you know what I mean.
Anyway, here is one of the most fiendishly difficult arrangements ever done for the piano as done and played by Vladimir Horowitz.
It is so difficult, that even Horowitz did not play it much as an encore. He said it was too damn difficult.
Three staves and multiple lines on each one. You would swear there are more than two players playing it. Just one. Horowitz.