The legendary pianist Vladimir Horowitz always took two pianos on tour, but not for use on the same program.

WSJ: When Two Makes Perfect | By Byron Janis

Ms. ALSOP: You hear in this piece the Stravinsky rhythms, and this idea of using two pianos is quite unusual and...

NPR: The Lasting Appeal of Orff's 'Carmina Burana'

He wanted it to be a piece for all of the senses: to hear the voice, to hear the words, to experience this enormous orchestra, two pianos.

NPR: The Lasting Appeal of Orff's 'Carmina Burana'

Like the time he dreamt he was driving up Interstate 5 in California and was approached by two black stretch limousines, which turned into pianos and blared arpeggios from their windows.

NPR: John Adams: 'Grand' And 'Gnarly' In Concert

We don't have that on our pianos, where even with the shift the hammers still strike two strings.

WSJ: Plumbing the Depths of Beethoven | Richard Goode | Cultural Conversation by Stuart Isacoff