Trisquel has replaced the Ubuntu name since software update

Since my last software update, the name Gnu/Trisquel has replaced Ubuntu at the top of the bootloader menu. Error reports now read "Sorry, Trisquel 6.0.1 has experienced an internal error."

I allowed unofficial sources during the update. Why did this happen? What should I do about it?

Output of sudo apt-get update:

sudo apt-get update
[sudo] password for j: 
Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease

Hit:2 http://deb.opera.com/opera-stable stable InRelease                       
Hit:3 http://archive.canonical.com/ubuntu xenial InRelease                     
Hit:4 http://dl.google.com/linux/chrome/deb stable Release                     
Ign:5 http://repo.vivaldi.com/stable/deb stable InRelease                      
Hit:6 http://repo.vivaldi.com/stable/deb stable Release                        
Hit:7 http://deb.bitmask.net/debian xenial InRelease                           
Hit:8 http://ie.archive.ubuntu.com/ubuntu xenial InRelease                     
Hit:9 http://ie.archive.ubuntu.com/ubuntu xenial-updates InRelease             
Hit:10 http://ie.archive.ubuntu.com/ubuntu xenial-security InRelease         
Hit:11 http://ie.archive.ubuntu.com/ubuntu xenial-backports InRelease        

Hit:12 https://deb.opera.com/opera-stable stable InRelease                   
Hit:13 https://repo.skype.com/deb stable InRelease 
Hit:14 https://downloads.iridiumbrowser.de/ubuntu xenial InRelease
Hit:15 https://repo.windscribe.com/ubuntu xenial InRelease
Hit:16 https://downloads.iridiumbrowser.de/deb stable InRelease
Get:19 http://mirror.fsf.org/trisquel toutatis-updates InRelease [5,487 B]
Ign:19 http://mirror.fsf.org/trisquel toutatis-updates InRelease
Fetched 5,487 B in 4s (1,293 B/s)
Reading package lists... Done
W: Target Packages (multiverse/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134

W: Target Packages (multiverse/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Packages (multiverse/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Translations (multiverse/i18n/Translation-en_IE) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Translations (multiverse/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target DEP-11 (multiverse/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target DEP-11-icons (multiverse/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
N: Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'https*://downloads.iridiumbrowser.de/ubuntu xenial InRelease' doesn't support architecture 'i386'
W: GPG error: http://mirror.fsf.org/trisquel toutatis-updates InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B4EFB9F38D8AEBF1
W: The repository 'http://mirror.fsf.org/trisquel toutatis-updates InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.

N: See apt-secure(8) manpage for repository creation and user configuration details.
W: Target Packages (multiverse/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Packages (multiverse/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Packages (multiverse/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Translations (multiverse/i18n/Translation-en_IE) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target Translations (multiverse/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target DEP-11 (multiverse/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Target DEP-11-icons (multiverse/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:93 and /etc/apt/sources.list:134
W: Duplicate sources.list entry http://deb.opera.com/opera-stable stable Release