With DDM 1.xx: while holding down the SHIFT key, right-click on the DDM system tray icon and in the popup menu UNcheck "Onscreen notifications".
I have a new Dell monitor at work and an old Dell monitor at home. The one at work used version 2 and the one at home uses version 1. I don't need a prompt telling me that this monitor isn't compatible at home or at work. The options I see are:
DDM, prompts about compatibility