It's not uncommon in this sort of situation for them all to get upvoted. Firstly, different people will upvote different ones, so if there's a popular story the

It's not uncommon in this sort of situation for them all to get upvoted. Firstly, different people will upvote different ones, so if there's a popular story then a large number of upvoters split by 3 is still a decent number on each. Then there are people who will upvote more than one, either because they think it's important enough to deserve multiple links, or because they think the links offer enough difference in content, or because they upvote the first one they see, then see there's a better one (e.g. "oh shit, I upvoted blogspam, better upvote the official one now")