The Super User question "Playing mp3 in quodlibet displays “GStreamer output pipeline could not be initialized” error" is indexed under two URLs in Google:
The first one is the canonical one; the corresponding
canonical is included in both pages:
<link rel="canonical" href="http://superuser.com/questions/651591/playing-mp3-in-quodlibet-displays-gstreamer-output-pipeline-could-not-be-initia" />
Google also indexed
http://superuser.com/a/652058, which redirects to the answer:
Now, the second URL from above is the same as this one minus the fragment
So Google seems to strip the fragment, which results in exactly the same page under another URL (= containing the answer ID
/652058 as suffix), and indexes it, too -- despite
canonical and duplicate content.
Shouldn’t Google recognize this and only index the canonical variant?
What is going on here?
EDIT: Google even displays a slightly different title for the same page (screenshot of result #1 and #2 for the query "Super User QuodLibet"):