"Earth Duo" is a remote collaboration between John Francis of the USA and Marcela Kadlecová of the Czech Republic. Marcela's vocal and melodica were added to John's seven-string guitar arrangement of "We Shall Overcome." "Jednou budem dal" is sung throughout the second verse. John produced the video. This tune became most closely associated with the civil rights movement of the USA, but its origins can be traced back to the late 18th century aria "Caro Mio Ben" by Giuseppe Giordini.