It just happened again to me in the "Free drinks for Diamonds/credit card holders?" thread in the DL forum. My post #3 appeared approximately one hundred times, all as post #3, in the thread (I tried to count them this time!), but again when I refreshed, all oof the duplicates disappeared.

This instance was different in that I saw echoes of my own post this time, rather than that of someone else with my own post temporarily not appearing. Again, it looks like someone else was making a post just as I was doing so.