When replying to a story (not to another post!) in CNET news.com usually what happens is that I get a page that says the page I requested was not found. Then If I go back in the browser and click the "submit" button again I get a notification that the post is a duplicate, but then at least I can navigate back to the story and the related talkbacks. Sometimes the reposting doesn't complain about duplicates but just posts a duplicate post (and then I am actually taken to that post and not to a "page not found" error message). I think the latter happens if there is a significant time delay between the posting and reposting (i.e., in the rare cases when I actually work between talkback ...
)

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic