When I enable security update it unchecks itself and $ apt-get update shows multiple duplicate security updates.

Hello people,

I'm having a problem with my fresh installation of eOS, and it is about the Software & Updates menu.

Every time I install eOS I always go to the Software Updater to change the settings. In the Software & Updates window I do the following things in each tab.

Ubuntu software tab
I always leave it as it is. Everything by default

Software sources tab
I always enable the "Canonical Partners" and "Independent" options. Sometimes I also enable the Source Code options of the two.

Updates tab (this is where everything goes haywire)
I always enable the "Important security Updates (trusty-security)" and the "Recommended Updates (trusty-updates)" options and I don't change anything else in this tab. When I click the check-box to enable those two options they show the tick symbol as supposed but as soon as the tick symbol appears it disappears and I don't know if the options are enabled or not. After the clicks I open the terminal and always do the apt-get update. after updating the sources I get this message.

Fetched 33,6 MB in 1min 24s (399 kB/s)
Reading package lists... Done
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_main_binary-amd64_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/universe amd64 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_universe_binary-amd64_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/multiverse amd64 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_multiverse_binary-amd64_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/restricted amd64 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_restricted_binary-amd64_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/main i386 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_main_binary-i386_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/universe i386 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_universe_binary-i386_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/multiverse i386 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_multiverse_binary-i386_Packages)
W: Duplicate sources.list entry http://security.ubuntu.com/ubuntu/ trusty-security/restricted i386 Packages (/var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_trusty-security_restricted_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems

It seems that when I clicked those option I've enabled them again and created a duplicate entry in the config file.

My questions are.
If I don't enable them by clicking are they enabled by default? and if they are enabled by default why don't they show the tick symbol like the other options that are enabled?

Thanks in advance.