Maybe duplicates do get removed. (I thought that generally only one at a time would get upvoted.) But not within half an hour.
If you're thinking that it was only submitted once, and a bug is causing it to appear multiple times --- they are clearly different submissions: different scores, different submitters (though you've cropped that out), even different titles (the dashes are different).
Here's what I thought - If you post something with the same external link, the post will deleted if the earlier one was posted within certain interval, say two days.