If there are multiple new posts on a thread, they are shown individually in the results, which is why you'll sometimes see duplicates or more.
Unfortunately the confusion arises because the information displayed in the listings is exactly the same for each entry. Ideally it should show different post date/time information for each post, but it doesn't at the moment.
This is another of the idiosyncrasies of the new software, but one that has been mentioned in the developers forum and may well be ironed-out in future updates.
Cheers,
Shaun