From archive.org:

“In 1967, Steve Reich composed a “Piano Phase”, a piece of music for two pianos. It was his first attempt at applying the phasing technique to live performance. Two pianists are playing a rapid twelve-note melodic figure over and over again in unison. As one player precisely keeps the tempo, the other speeds up very slightly until the two parts line up again, but one sixteenth note apart. The second player then resumes the previous tempo. This cycle of speeding up and then locking in continues throughout the piece; the cycle comes full circle three times, the second and third cycles using shorter versions of the initial figure.

But on October 2006, Russian pianist Peter Aidu performed this composition with an absolutely unique technique. While playing on two pianos, with a left hand on one instrument and the right hand playing separately on the second piano, he was recreating the sounding of two performers! This tremendous act was accurately recorded, and now is available exclusively from top-40.org.”

It doesn’t bump or anything but props to the player, and pretty cool early experiment with phasing in a live environment.