Project Wild Penguin 17.4.2017: Fix duplicate sources.list entry
To fix the above mentioned error, follow the list of steps that most easily provides the solution (also to backup PPA repository and other features too): You can remove duplicate entries in few easy steps with Y PPA Manager sudo add-apt-repository ppa:webupd8team/y-ppa-manager -y sudo apt-get update sudo apt-get install y-ppa-manager -y Open y-ppa-manager form Dash Enter You Admin Password. Double Click On Advanced. Scan & Remove Duplicate PPA's & Click Ok. It will take some time ( 1 or 2 Mints ) To Scan & Remove Duplicate PPA's. Source: https://askubuntu.com/questions/120621/how-to-fix-duplicate-sources-list-entry