there is no way they double sent coins to the tune of ~740,000 bitcoins. Once Customer Service gets a few thousand emails about resending coins they'd sure check to see what is up. Why would a company allow deposits and not withdrawals in it's waning hours, they knew the ship was sinking and they kept taking more passengers. It's exactly how Full Tilt, Ultimate Bet, and 50 other online sites did in their last hours. The thing is these other companies used those deposits and user balances to pay themselves hefty salaries and operational expenses. 740,000 bitcoins is a ridiculous amount of money, if they were shady they'd only need a fraction of that for salaries or operational expenses.
It's speculation but to me one of the ways someone can lose that much is if they are some how gambling/trading with user balances. Once he/they got in a hole and tried to gamble/trade himself out of it he couldn't stop.