Of course, the cause could also simply be that they are retards and their system simply sent the 2nd transaction after it 'thought' the first one failed ... so there was no fraud/theft, it was simply a crap system sending BTC to people multiple times.
that wouldnt happen over years / 750k btc without one feedback from the community
Exactly. There has been a stunning silence from all the people who supposedly received double payouts from mtgox. Knowing this community there would have been some yahooing about it straight-away.