What is "Multi" about?

I have had The Grand for a while but rarely used it. I am now spending more time with it and I have a question for y’all. In the list of presets there is a “Multi” option. What is it used for? As far as I can see you can only load one instrument at a time. I can’t find any information about this in the manual.

I am sure I am missing something very simple here but my brain is stuck. Anyone to the rescue? :wink:

I wonder as well what the Multi is for…