Why does "Open With" display so many instances of an app?
Rebuild LaunchServices to Fix Duplicate Entries in OS X’s ‘Open With’ Menu


  To fix this, we need to reset OS X’s LaunchServices database. As is the case with most actions in OS X, there are multiple ways to accomplish this task, but the fastest is to simply use a Terminal command.


From that article- Copy following in to your Terminal

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