It got submitted at least three times.

Duplicate links do get submitted.

But, I thought they are removed. And both of these links were posted at the same time (reads 29 minutes ago).

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).

Ofcourse, they can be submitted multiple times.

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.