To reproduce this you need to position the desktop alert on a monitor different than the primary one. Also, the DPI scale settings on the monitors should be different. For example, the primary one can have 100% and the second one 125%. The "dpiAwareness" setting also affects this behavior.
To work this around, you can host the RadDesktopAlert control in a new Window control instead of using the RadDesktopAlertManager. This will give you full control over the alert window's position. In this case the built-in dragging and auto-closing won't work, so it should be implemented manually.
Want to add multiple Buttons/Commands without changing whole style.
Like: https://docs.telerik.com/devtools/winforms/controls/desktopalert/button-items
This would make it possible to generate some sort of summary of Alerts that have been displayed
With the current implementation is not possible.
Available in LIB version 2015.3.1116, it will be also available in the 2016 Q1.