I'm using an Arduino Due with Ethernet Shield v2. Accoring to the unofficial pin layout diagram the SPI communication goes via the "SPI" (MISO, MOSI, etc.) header.
Consequently the SPI interface MISO2, MOSI2, etc. on the "ICSP" header are free for usage.
However in the source code of the Arduino Due Board Support package I was not able to find some reliable info about if the second interface is supported by the SPI.h lib. According to some pin mapping it's not.
SPI.h libb support the second SPI interface of the Arduino Due?