Two people playing on one piano is no problem. I do that often with my grandchildren. But what about two people playing one guitar? Love the way one of them is playing the 'bass part' in this one.

Four Hands Guitar



And here's another one ...

Tico Tico no Fubá - Duo Siqueira Lima - 4 Hands

Very Accomplished players, sounds good. Better than my playing. Den.