I've never gotten one to make what I am thinking of:
A Galton board. At the top, several inches apart are two holes from which balls drop. One drops blue balls, the other red balls. They form a merged distribution below in columns, demonstrating dual overlapping normal distributions
Imagine one of these: https://imgur.com/a/DiAOTzJ but with two spouts at the top dropping different colored balls
Its attempts:
https://imgur.com/undefined
https://imgur.com/a/uecXDzI