Remove duplicates from Finder "Open With"

Add to your .bashrc:

alias cleanopenwith='/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user'

Restart terminal.

Run: cleanopenwith

If you still see duplicates restart finder: killall Finder

If running cleanopenwith gives you an error (not found) try running
source ~/.bashrc and then run cleanopenwith again.