"Dual-link" is described as follows in AD9398 Datasheet Rev. 0 | Page 27 of 44 .
"0x27—Bit HDCP A0 Address
This bit sets the LSB of the address of the HDCP I2C. This should be set to 1 only for a second receiver in a dual-link configuration. The power-up default is 0."
Please instruct the "dual-link configuration" circuit diagram.