This is correct interpretation, you can have stereo output but your instrument can handle only one note at the time. There are plenty of modern synths that hav

This is correct interpretation, you can have stereo output but your instrument can handle only one note at the time. There are plenty of modern synths that have "mono" or "solo" option. If you play two notes at once, the resulting tone will slide from first note to the second. This is obviously very useful for playing melodies and keyboard solos where polyphony is often not desired. BTW there are ways to use multiple mono-synths as a poly-synth, depending on VST host.