如何解决错误重复sources.list？

Question

sudo apt-get update会抛出这个错误

Ign http://us.archive.ubuntu.com trusty/universe Translation-en_US             
Reading package lists... Done                                                  
W: Duplicate sources.list entry http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg/main amd64 Packages (/var/lib/apt/lists/apt.postgresql.org_pub_repos_apt_dists_trusty-pgdg_main_binary-amd64_Packages)
W: Duplicate sources.list entry http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg/main i386 Packages (/var/lib/apt/lists/apt.postgresql.org_pub_repos_apt_dists_trusty-pgdg_main_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems
miravm@ubuntu:/var/lib/apt/lists$ 

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我相信这与postgres有关。我该如何解决这个问题？