If those things are interesting enough to people (including those reading them for the first time on the nth posting), to be upvoted multiple times, then it's not "gaming the system".
What we should care about is if we have interesting articles to read -- and if people that might have missed something in the past have a chance to see it, that's for the better.
There have beens lots of very lively discussions on the 3rd and 4th posting of the same story, and I wouldn't want those people to miss the post entirely, or those conversations to never happen.
As for the duplicate poster getting points from something he knows will be popular again, well, nobody cares if he does get the points. HN is not some silly high score competition.
