The following Terminal command does work, but only for a short time. After a day or two, the duplicates return, even without any restarts.

TO REBUILD LAUNCH SERVICES:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain user;killall Finder;echo "Open With has been rebuilt, Finder will relaunch"

TUAW source:
http://www.tuaw.com/2013/03/25/how-to-spring-clean-open-with-duplicates/

I am wondering if the duplicates might get restored somehow because my Applications folder is not in my individual user folder; it's in my 'Macintosh HD' folder - perhaps because the apps were installed for "All Users?" I am very hesitant to move my apps from where they are.

My admin account is separate from my regular user account.

Thanks for any help.

I am on Mavericks on a MBP.

Hap

Sorry. I should add that this problem did not arrive with Mavericks. It's been around for quite some time.

Hap

Don't move your apps. If duplicates are coming back, you most likely have more than one copy of the application installed, possibly on another boot drive or backup.

Thanks, Kevin -

The only app copies I have are on a SuperDuper backup drive, though I only plug that drive in and do backups occasionally.

FWIW, I'm convinced these duplicate references are being picked up, at least in my case, from external clones / boot drives. I periodically run the Terminal deletion command; and then, after completing a subsequent, Superduper clone (to an existing, external drive clone that's either dismounted or disconnected when the deletion was done) these duplicates reappear.

I've since discontinued worrying about this visual bother as I know my internal drive does not have actual duplicates. ...What me worry.

Plugging in your backup drive occasionally is enough to make the Open With... menu pick up the copies on your backup drive! I use Carbon Copy Cloner to back up my computer, and, like you, I also see these duplicate entries.

If you add the cloned/backup application folder to the Privacy tab in the Spotlight System Preference, it should keep it from re-appearing after a Launch Services rebuild unless the Application is directly launched from the cloned/backup location.

Many thanks for the suggestion. Will give it a shot when I get my Mac back from the repair shop in a few days.

Thanks again.

Hap

Great recommend. Thanks.

So far, the problem seems to have been solved. Using the Privacy tab of Spotlight preferences, I excluded the entire SuperDuper backup drive, and a folder on my Mac called 'Developer-old' which was producing duplicates in the 'Open With' list.

Thanks for the help on this.