Why I am seeing two Twitterrific application icons in the Dock? (Mac)

This issue is caused by hiding the Twitterrific icon in the Dock. When you add Twitterrific to your login items and have the Dock icon hidden, sometimes a second Twitterrific Dock icon will show up when you next start your computer. The only permanent solution to this issue is to remove Twitterrific from your login items list, or to re-enable the application's Dock icon.

If you wish to keep the Dock icon hidden and don't want to remove Twitterrific from your login items, you can temporarily solve the issue by restarting the Dock via the Terminal. To do this:

  1. From a Terminal (found in your Utilities folder in your Applications folder) enter: sudo killall Dock
  2. Enter your administrator password and the Dock will disappear and reappear without the second icon.