This performance of Steve Reich's 1967 seminal minimalist piece 'Piano Phase' on two marimbas was recorded at the same concert (October 22nd 1976, Salle Wagram, Paris) as the recording of 'Music for 18 Musicians' I previously uploaded here:    • Steve Reich - Music for 18 Musicians ...  

The performers are either Russell Hartenberger and Jim Preiss (pictured) or Russell Hartenberger and Bob Becker -- the pairs alternated from concert to concert.

I recommend reading this article by Russell Hartenberger on his experience of playing this piece and how the arrangement came about: https://www.drummingat50.com/2020/10/...