Potential work around for the Catalina Mac OS update
I'm unsure if someone has already suggested this, but with the latest update Mac has rolled out (for Catalina 10.15), my DisplayLink stopped working with dual screen.
I have updated the driver to the most recent release, and all that would display would be one of the two screens. DisplayLink lists a possible solution involving entering recovery mode and inputting commands, however, I am impatient and lazy and did not do that.
But, I did get my dual display working again. For me, toggling my displays to mirror activated my dual screens, and toggling off mirroring has left my dual screens functioning as they should.
I don't know if this will work for anyone else, but it did for me, and it took 2 seconds to test, so it might be something to try before rolling out recovery mode.