There are numerious ocasions where either intended or unintended there are multiple ways of getting to the same output.

A few common examples of URLs that should have a canonical link in the head:

• http://commons.wikimedia.org/?title=Commons:Sandbox
• http://commons.wikimedia.org/w/index.php?title=Commons:Sandbox
• http://commons.wikimedia.org/wiki/Commons:Sandbox?action=view
• etc.
  • Canonical: http://commons.wikimedia.org/wiki/Commons:Sandbox

Perhaps these unindex ones as well:

• http://commons.wikimedia.org/wiki/Commons:Sandbox?action=edit
  • Canonical: http://commons.wikimedia.org/w/index.php?title=Commons:Sandbox*action=edit
• http://commons.wikimedia.org/?diff=46399545
  • Canonical: http://commons.wikimedia.org/w/index.php?diff=46399545
• http://commons.wikimedia.org/wiki/Special:Contributions/Krinkle?namespace=6
  • Canonical: http://commons.wikimedia.org/w/index.php?title=Special:Contributions&target=Krinkle&namespace=6

Version: 1.17.x
Severity: minor