Duplicated dock icons on Ubuntu 20.04 when I unlock the screen

When I unlock the screen on my Ubuntu 20.04, every app icon is duplicated(picture link below)

My extension: Dash to Dock

My customisation:

• Theme: Adapta-Cyan-Nokto-Eta
• Icons: OieIcons

I use tweaks

Ubuntu 20.04 dock

I did some research(this link below): 
https://askubuntu.com/a/975230/1109086

But still the same thing. It happens only when I unlock the screen; when I reboot the laptop or log out and log in again, the docks are not duplicated.