Having two Google Chrome icons in Plank is mostly as a result of installing Google Chrome by downloading the .DEB file form Google’s website and running dpkg command on it. The .deb file downloaded name contains stable as in google-chrome-stable_current_amd64.deb.
First open terminal and run the command below to edit the .desktop file of Google Chrome:
sudo vi /usr/share/applications/google-chrome.desktop
Locate the line with code as shown in image below:
Change it to the code below and save: (By simply deleting –stable)
Finally, close all instances of running Chrome windows and also remove Chrome from plank when you have selected the “Keep in dock“.