Some music producers use two monitors (or more) because it can be very helpful to separate the workspaces of a DAW program into separate windows and then place those windows on their own monitor. A common scenario detaches the DAW mixer into a separate window that goes onto its own display, while the DAW track timeline has its own monitor. Particularly for complex productions, that gives producers more dedicated space to work on track automation or zoom in on tracks to edit them in the timeline, and to have a large view of the mixer and/or instrument and effect plug-ins. More monitor space can save time from clicking around to collapse and expand DAW windows while working. If they’re scoring/sound designing/mixing to picture, the artist will also often have a third display dedicated to video playback.