It’s anoying if the app shows double when you do right click > open with within Finder. To solve this use this simple command:

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

Open up Terminal, copy and paste the code above then press enter. Wait until the process done, then you can quit the Terminal. The doubles (or triples) gone now.