After updating Xcode to 6.1, my launcher was having two icons for Xcode.
here is a quick “how-to” that helps removing duplicate applications in LauchPad:
Open a Terminal (Applications > Utilities > Terminal.app)
Type the following commands:
sudo rm ~/Library/Application\ Support/Dock/*.db sudo killall Dock
After what there should not be any duplicate
Remove Duplicate Icon form Launcher on OS X Yosemite
Super, thank you
This works, but it also has undesirable side effects, such as losing your wallpaper, and maybe other settings. It might be better to delete database files more selectively.