This really isn't of utmost importance, but thought that if anyone had a quick solution it'd be nice. For some reason I'm seeing double on a few items here in the right click menu for pixelmator and flickery
Are you certain you do not have 2 copies of the app installed? A simple way to check would be to launch each of those off the menu, right-click the Dock icon, go to
Options > Show in Finder and examine the file path.
If you don't have duplicate copies, then you might want to use your favorite maintenance utility (Onyx, MainMenu, IceClean, etc) to do some housecleaning. Updating the Prebindings and the Locate Database in particular might fix this.
If you have OS X installed twice on your computer, as a dual-boot solution, then it could be related to that. I have a backup install, and every now and then, I accidentally get double-entries like that off the backup. Running those maintenance utilities may help in clearing that up.