I cannot see how that could have been done accidentally. But then again I have seen ground support personnel do some incredibly stupid things.
I would more suspect an act of sabotage by a disgruntled employee verus an act of terrorism. Either way, it will be a real pain to flush out all of the potable water systems on all the aircraft affected.
As for similar incidents, just recall how many piston powered aircraft have fueled with Jet A in the past.