Two of my own withdrawals ended up at 18Yrkm5cRqT1MiqwAUBDcN64hWb1pLutsW and 1P62VZZ9kL97dzzcWhG7JZDssaW2MDgn8 too.
The transaction which eventually led to my BTC withdrawal also had a concurrent transaction ending at this address: 3HxJoT5L3aSuKKzNaLWyPiPVyZ6UJRVZGd
And a further update...One of the upstream wallet addresses has been receiving some BTC from freebitco.in.
https://blockchain.info/address/1Jxj7VJxVBPZTHJkff6yhGYxTYGvWy3mnH