The second display is illegal. Why so?

The second display usage is prohibited until the exam is over. If you have more than one display connected to your PC or laptop, please unplug extra display (or displays) so that only one remains connected. To turn off extra displays quickly on Windows, use the “Win+P” short key and select “PC screen only”:

To turn off an extra display on macOS, turn off it manually and disconnect its HDMI cable.