Both postings were the same URL, posted by different users, each with less than ten upvotes and zero comments, on the homepage simultaneously within ~10 spots o

Both postings were the same URL, posted by different users, each with less than ten upvotes and zero comments, on the homepage simultaneously within ~10 spots of each other. I wasn’t being critical of the project (actually quite the opposite), more surprised at the situation. According to what it shows, one was posted 12hrs ago, the other was 10hrs ago, so why wasn’t the second submission two hours later by a different user handled appropriately? You’d think that they’d at least have logic to prevent the exact same url from showing up on two different submissions at the same time.