Thought I have not tested it the Due can configure different clock divider values to CS pins so you can still use a single MISO, MOSI & CLK but the CS pin defines the clock for that chip http://arduino.cc/en/Reference/DueExtendedSPI
Thought I have not tested it the Due can configure different clock divider values to CS pins so you can still use a single MISO, MOSI & CLK but the CS pin defines the clock for that chip http://arduino.cc/en/Reference/DueExtendedSPI