Have you ever heard of a grand piano with a double keyboard? Would you like to know for what purpose such an instrument was created? Let us explain everything! 
The system was invented by Emanuel Moor in the 1920s and 1930s. In this type of instrument, fragments of an octave are distributed between two keyboards and theoretically the arrangement of the keys makes it easier to play works by such composers as Rachmaninov, Chopin or Bach.
Emmanuel Moor – Composer and inventor
Who was Emanuel Moor? He was born on the 19th of February 1863 in Kecskemét, Hungary. He was a Hungarian composer, pianist and creator of musical instruments. His best known invention is the Emanuel Moor Pianoforte, which consists of two keyboards lying one above the other.
Moor studied in Prague, Vienna and Budapest. Between 1885 and 1897 he gave concerts in Europe and the United States. Apart from his five operas and eight symphonies, he also wrote concerts for piano, violin, cello, viola and harp. He died in 1931 in Chardonne, Switzerland. His wife, the pianist Winifred Christie-Moor, was a tireless promoter of the Emanuel Moor Pianoforte in Europe and North America long after his death.
What does such a grand piano look like? It has 164 keys, four pedals…
Oh yeah… and two keyboards.
The double piano keyboard makes it sound louder. Unlike the organ, it has only one set of hammers and strings. On the shorter, higher-placed keyboard, the notes are played an octave higher. Due to the way the keys are arranged, one above the other, it is possible to extend its range considerably beyond what is possible on a traditional keyboard. So you can cover the range of two octaves by playing e.g. C on the lower keyboard with your thumb and C on the upper keyboard with your fifth finger.
Several leading piano manufacturers have been tempted to make at least one copy of such an instrument. Moor’s idea inspired Steinway, Bosendorfer, Pleyel, Bechstein and Chickering, among others. However, only 60 pianos with Moor’s double keyboard were produced worldwide. The mechanism diagrams were probably already lost, at least by Steinway, during the bombings of World War II.
Initially, every piano manufacturer in the United States and Europe rejected the design of a double keyboard, claiming that it would be impossible. Moor made the prototype on his own, only with the help of a carpenter.
The problem, however, is that every pianist would have to learn to play their entire repertoire anew. The idea of producing the instrument on a larger scale was doomed to failure practically from the beginning and to this day remains only a musical curiosity.
Very interesting info! Perfect just what I wass lookiong for!