This issue might occur after upgrading from
macOS Mojave to macOS Catalina.
The user will see a black screen or single functioning DisplayLink device, despite the fact that two of them are plugged-in and both are visible in macOS Display Preferences.
In order to fix this problem please perform the following steps:
1. Uninstall DisplayLink Software
2. Go to the macOS Recovery Mode.
* macOS Recovery is part of the built-in recovery system of your Mac. You can start up from macOS Recovery and use its utilities to recover from certain software issues or take other actions on your Mac.
How to enter macOS Recovery Mode
3. Run the "Disk Utility" application from the window with applications selection by clicking on it
4. You should then see this Window
5. If you have FileVault enabled, or if for any reason the first internal drive is not mounted please mount it.
6. Please close the application "Disk Utility" by clicking on the red button in the top left corner of the Disk Utility windows - just as normal as you're closing the application.
7. Please run "Terminal" Application from the Top Menu Bar.
8. You should then see Terminal application window
9. Now, it's time to execute single command which help to rebuild the system cache, which is a cause of the issue
10. After few seconds you should see similar output
It is OK when you see the last line with KernelCache ID.