Winklevoss twins cut up their Bitcoin key and keep the pieces in different bank vaults across America to protect their $1.3billion digital fortune Tyler and Cameron Winklevoss, 36, started buying up Bitcoin back in 2012 They used $11m to buy roughly 120,000 Bitcoins when they were less than $10 The funds for Bitcoin came from the $65 million settlement they reached with Facebook's Mark Zuckerberg Twins have cut up the keys to their digital fortune and keep each piece in…