How can I fix apt error "W: Target Packages ... is configured multiple times"?

I just installed Ubuntu Gnome 16.04. I told it to save my documents - which worked. Some software had to be reinstalled. Now when I run sudo apt-get update I see this:

W: Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (main/i18n/Translation-en_GB) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11 (main/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11-icons (main/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (restricted/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (restricted/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (restricted/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (restricted/i18n/Translation-en_GB) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (restricted/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11 (restricted/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11-icons (restricted/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (multiverse/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (multiverse/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (multiverse/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (multiverse/i18n/Translation-en_GB) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (multiverse/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11 (multiverse/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11-icons (multiverse/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: The repository 'http://extras.ubuntu.com/ubuntu xenial Release' does not have a Release file.
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: http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg: Signature by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 uses weak digest algorithm (SHA1)
W: http://repo.sinew.in/dists/stable/InRelease: Signature by key B6DA722E2E65721AF54B93966F7565879798C2FC uses weak digest algorithm (SHA1)
E: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/xenial/main/source/Sources  404  Not Found [IP: 91.189.92.152 80]
E: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not Found [IP: 91.189.92.152 80]
E: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found [IP: 91.189.92.152 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
W: Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (main/i18n/Translation-en_GB) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11 (main/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11-icons (main/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (restricted/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (restricted/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (restricted/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (restricted/i18n/Translation-en_GB) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (restricted/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11 (restricted/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11-icons (restricted/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (multiverse/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (multiverse/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Packages (multiverse/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (multiverse/i18n/Translation-en_GB) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target Translations (multiverse/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11 (multiverse/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87
W: Target DEP-11-icons (multiverse/dep11/icons-64x64.tar) is configured multiple times in /etc/apt/sources.list:33 and /etc/apt/sources.list:87

Is there an automated way to fix this?

Recent, up-to-date solution

I wrote a Python script to automate this task. You can find the most recent version here.

Installation:

1. Install the prerequisites:

   sudo apt install python3-apt
   

2. Download the PYZ bundle (aptsources-cleanup.pyz) from the latest release.

3. Mark the PYZ bundle as executable:

   chmod a+x aptsources-cleanup.pyz
   

Usage:

1. From the download location of the PYZ bundle (see step 2 above) run:

   sudo ./aptsources-cleanup.pyz
   

2. Follow the instructions appearing on the screen.

If you wish to report an issue, leave a comment, or fork the source code, please do so on GitHub.

Historical, outdated solution

This is an older, shorter and simpler version more suitable to inline quotation:

#!/usr/bin/python3
"""
Detects and interactively deactivates duplicate Apt source entries.

Usage: sudo python3 apt-remove-duplicate-source-entries.py
"""

from __future__ import print_function
import aptsources.sourceslist

EMPTY_COMPONENT_LIST = (None,)

def get_duplicates(sourceslist):
    """
    Detects and returns duplicate Apt source entries.
    """

    sentry_map = dict()
    duplicates = list()
    for se in sourceslist.list:
        if not se.invalid and not se.disabled:
            for c in (se.comps or EMPTY_COMPONENT_LIST):
                key = (se.type, se.uri, se.dist, c)
                previous_se = sentry_map.setdefault(key, se)
                if previous_se is not se:
                    duplicates.append((se, previous_se))
                    break

    return duplicates


if __name__ == '__main__':
    try:
        input = raw_input
    except NameError:
        pass

    sourceslist = aptsources.sourceslist.SourcesList(False)
    duplicates = get_duplicates(sourceslist)

    if duplicates:
        for dupe, orig in duplicates:
            print(
                'Overlapping source entries:\n'
                '  1. {0}: {1}\n'
                '  2. {2}: {3}\n'
                'I disabled the latter entry.'.format(
                    orig.file, orig, dupe.file, dupe),
                end='\n\n')
            dupe.disabled = True

        print('\n{0} source entries were disabled:'.format(len(duplicates)),
            *[dupe for dupe, orig in duplicates], sep='\n  ', end='\n\n')
        if input('Do you want to save these changes? (y/N) ').upper() == 'Y':
            sourceslist.save()

    else:
        print('No duplicated entries were found.')

It takes no parameter and works on all /etc/apt/sources.list* with the help of the python3-apt package. Lines don't have to be exact duplicates (even after normalization) but its enough if type, URI, suite and at least one component overlap.

I'm not sure the equality test is correct in all corner cases (e. g. various “option” strings).

For me (16.04 LTS) going to

System settings >> Software and Updates >> Other Software and removing each duplicate entry from the list worked fine.

Reset your repositories like this:

1. IMPORTANT: First verify that you have software-properties-gtk installed (you can run software-properties-gtk -h to verify that you get a help-message)
2. sudo mv /etc/apt/sources.list /etc/apt/sources.list.bak
3. sudo software-properties-gtk
4. Pick your options
5. Save

Once everything is working, you can then delete your backup with sudo rm -rf /etc/apt/sources.list.bak.

Since the errors tell you where the problem is, and that all the problems are due to a single duplicated line, you can easily fix this manually with a text editor like vim, nano, etc. One benefit of this is that you can see exactly what the problem is and what you're doing to fix it.

In your case, with sudo or as root, open /etc/apt/sources.list in a text editor. Delete either line 33 or line 87. You can visually check that they're duplicates first.

If you like vim...

$ sudo vim /etc/apt/sources.list
33 [Shift]+g    # to goto line 33
87 [Shift]+g    # to goto line 87, don't need a duplicate of line 33
dd              # to delete the line you're on
:wq             # to write the file and quit

Or, to get out if you make a mistake...

:q!             # to quit without saving any changes

For Ubuntu-based systems with Linux mint, go to Software Sources > Maintenance > Remove Duplicate packages

Similar to Other Answers, BUT ...

I had to look in /etc/apt/sources.list.d. Two of the list files in that directory were trying to reference the same things.

I kept the list file that was referencing more things. Problem solved.

Manually edit /etc/apt/sources.list and remove duplicated lines.

I do not think that this is a useful advice for your problem with the Ubuntu installer that you cannot control. Yet, if you just have this error after writing some installation commands yourself instead, this might perhaps help:

In a Dockerfile for a python2 ROS project and a lot of installed apt-get packages before the error, I got another error first: /bin/sh: 1: python-matplotlib: not found, although it is a known package in apt-get. Then I switched to python -m pip install -y matplotlib sympy which caused the error of the question: #13 3.422 W: Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list.d/ros-latest.list:1 and /etc/apt/sources.list.d/ros1-latest.list:1. At this point, you might consider testing python2.7 -m pip install -y matplotlib sympy as well according to this. Then I switched back to

apt-get install -y python-matplotlib python-sympy

and I also kept that line apart from other apt-get installations.

The steps may not all be needed, I just did not want to take out any of them since I can only guess the reasons. A small share of the finally working Dockerfile:

RUN apt-get install --upgrade python-pip -y && \
    python -m pip install --upgrade pip
# I have seen during installation that the default fell back to Python3.7 for at least one package:
RUN apt-get install -y MANY_PYTHON2_PACKAGES_PERHAPS_INSTALLED_WITH_PYTHON3.7_DEFAULT
# These packages perhaps need another Python version than the previous?
RUN apt-get install -y python-matplotlib python-sympy
RUN python -m pip install MANY_PYTHON2_PACKAGES_NOT_IN_APT-GET

UPDATE: I had the error again when update ran. I simply dropped the update. That worked because it had run a couple of lines before anyway:

From:

RUN apt-get -o Acquire::Check-Valid-Until=false update && \
    apt-get install -y ...

to

RUN apt-get install -y ...