I've seen in other posts that the code setup and HDL are exactly the same for the AD9361 and AD9364, plus they are pin interchangeable. The RX2B pins just need to connected to VSSA.
How is the AD9361 setup in 1rx1tx mode, i.e. two_rx_two_tx_mode_enable set to 0, different from the AD9364? Is the power consumption less?