ATmega328PB has one Additional SPI. There are two SPIs with individual configuration registers. Refer to the Register Description section in the SPI peripheral in the ATmega328PB device datasheet for detailed description of these registers. They also have a separate MOSI, MISO, SCK, and SS pins. Refer to the I/O Multiplexing section in the ATmega328PB device datasheet for details about the pin mapping for this peripheral.