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It was the same account on both chains. As the the coins transferred to my Bittrex account 0x4f7144b02273bdc4083b98ea075a5ab13fa9d4dd the transaction was replayed on the ETH chain. Have a look http://etherscan.io/address/0x4f7144b02273bdc4083b98ea075a5ab13fa9d4dd. As to how they got the coins out of that mirror account on ETH I have no idea. The must have found a way to create an ETH account for a specific address or something.

Only Bittrex could have transferred those funds. Only they had the key to the account. (Unless something much weirder is going on.)