14.04 - Not able to apt-get update

I'm trying to install postgreSQL BDR on my Ubuntu 14.04 following this simple guide: http://bdr-project.org/docs/next/installation-packages.html

I've done the steps provided which was:

1. Adding deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main to /etc/apt/sources.list.d/2ndquadrant.list




2. Importing repository key




3. sudo apt-get update

However, for some reason, running the last command produces a following output:
https://gist.github.com/mbajur/416588a165d62c17e9f0

That's awkward because i'm able to find exact the same tutorial for various of packages so it seems to be quite common thing to use that source.

What's the common way of dealing with such issues? Thanks in advance for any clues!

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Edit #1

My list files:

/etc/apt/sources.list

deb mirror://mirrors.ubuntu.com/mirrors.txt trusty main restricted universe multiverse
deb mirror://mirrors.ubuntu.com/mirrors.txt trusty-updates main restricted universe multiverse

deb mirror://mirrors.ubuntu.com/mirrors.txt trusty-backports main restricted universe multivers      deb mirror://mirrors.ubuntu.com/mirrors.txt trusty-security main restricted universe multiverse

/etc/apt/sources.list.d/apt_postgresql_org_pub_repos_apt.list

deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main

/etc/apt/sources.list.d/2ndquadrant.list

deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main

I've just noticed that those two last files has duplicated contents (might that be an issue?) but i'm not able to install given package anyway so there is something not right in here.

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Edit #2

I'm accepting A.B. answer but the real issue was that it seems that guys from postgres-bdr gave us wrong deb URL. It should be deb http://packages.2ndquadrant.com/bdr/apt/ wheezy-2ndquadrant main, not deb http://apt.postgresql.org/pub/repos/apt/ wheezy-pgdg main. That's why i was not able to install postgresql-9.4-udr-plugin package.

That are two different things. The repository

deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main

works as you can see in your gist.

The problem is that the mirror ftp.unina.it doesn't exist in the list of the defined mirrors.

Use a different mirror or the main server

sudo sed -i 's/mirror:\/\/mirrors.ubuntu.com\/mirrors.txt/http:\/\/archive.ubuntu.com\/ubuntu/' /etc/apt/sources.list

Remove /etc/apt/sources.list.d/apt_postgresql_org_pub_repos_apt.list,

the content is identical with the content of etc/apt/sources.list.d/2ndquadrant.list

sudo rm /etc/apt/sources.list.d/apt_postgresql_org_pub_repos_apt.list

Update the software sources

sudo apt-get update