Comment 4 for bug 657656

With the bare command:

delan@delan:~$ /usr/lib/update-notifier/update-motd-updates-available

delan@delan:~$

With sudo:

delan@delan:~$ sudo /usr/lib/update-notifier/update-motd-updates-available
[sudo] password for delan:

delan@delan:~$

With sudo and --force:

delan@delan:~$ sudo /usr/lib/update-notifier/update-motd-updates-available --force

0 packages can be updated.
0 updates are security updates.

delan@delan:~$

It only shows once. However, whatever script calls this script, may be calling it twice.