No option to duplicate monitors on Windows 10
The ability for a graphics card to duplicate its display to another graphics card was not a mandatory feature for graphics card drivers until the Windows 10 graphics driver model. Therefore some older graphics drivers, which have not been updated for Windows 10 may not support duplicate mode with DisplayLink. Examples are Intel Ivybridge and Intel Bay Trail graphics drivers for Windows 10.
Workarounds to this issue are to use a 3rd party tool to mirror the screens, for example Actual Multiple Monitors or to uninstall the graphics driver, so the system uses the Microsoft Basic graphics driver, which supports mirroring with DisplayLink.