I've been watching some of the E3 videos and several of them have duplicate posts in the comment thread. Chubbaluphigous' post here, MrMazz's post here, etc. I originally thought every post was duplicated exactly three times, but some of them are only doubles, for example in this video. Also, the duplicates have different timestamps - sometimes about a minute apart. If I had to take a wild guess, it seems like maybe this is a symptom of posts not showing up properly, causing people to press the "Post Reply" button repeatedly before they realize their mistake?
Actually, it's happening in normal forum threads too ("Shots fired" post).
Unfortunately I haven't experienced this phenomenon myself (seems to happen in maybe 10-20% of posts), so I don't know more about when or how it happens.