How to show desktop files on both screens?

I'd like to do the same thing, but I haven't found a way. The best compromise I could come up with was to move the menu bar to my primary display. By moving the menu bar, I changed the display which shows my dock and desktop files.

You can move the menu bar by dragging white bar in the Arrangement settings from one display to another:

This worked for me to move the dock at the bottom of the screen with icons from one screen to another (not the folders though): Move your mouse arrow to the very bottom of the display where you want your dock to appear and hover it there for a couple seconds. The dock will move off your primary display and appear on your other display.