If someone visits a question without an answer, that is closed as a duplicate, the person will automatically be sent to the original question. Consequently, it will be impossible to view the contents of the newer question. However, if the newer question received one or more answers posted before being closed as a duplicate, the page and the answer(s) posted will be visible.
For example, when I am logged out, I cannot see the following question:
Instead, the system directs me automatically to the “original” question
The same situation is repeated when visitors and logged-out users click on the question:
they will be transported to
- Add data.SE style "magic links" to comments and its single answer.
On the other hand, a question which has been closed as a duplicate of two older questions, for instance What's going on with the Announcer badge? will not automagically redirect the visitor (or the logged-out user) to the older posts.
I checked to see if this was by design in the FAQ
How should duplicate questions be handled?
The most relevant piece of information that I could glean was
Should duplicates be deleted? In general, no: most duplicates stay around. Having multiple copies of the same question with different wording is useful as search fodder, because people looking for an answer may use different wording too.
I also searched What is a "closed", “on hold”, or "duplicate" question? but found nothing which suggests a question that is closed as a duplicate appears "invisible" to visitors or users who are logged out of the site.
I tagged the question as a bug because it's unclear whether this feature is by design or not. If it is, I'm not terribly convinced it's a good idea. Not sure why a new question, which has been carefully composed and upvoted should not be useful to visitors.