Whilst browsing the site recently there are quite a lot of double posts. Is this a system glitch or is it that people are so excited about getting their point across they are hitting the "submit" tab too vigorously ?
It's both. There is a glitch which brings up an error page, and iirc refreshing has the effect of re-posting. Can't think of a good reason why the double-posters don't delete one of them, it's easy enough.