I've seen that bug before, but I doubt that happens at the same second. User "bitart" isn't in my list of people who sent Merit twice in one second.
It's obviously possible to do it slower than 1 second which would explain bitart's absence from the data. I was just thinking it would be odd if there was another bug that caused the same thing.
Double-clicking the button perhaps?
Ah the fat finger bug, I hadn't thought of that. It could be, now I need to find a post worth two merit to see if I can replicate it.