Dear Ken,
For most modern parts schematic diagrams are simplifications, aimed at explaining operation principle and showing relations between device pins. Protection devices are no exception. To provide our customers best protection performance with minimal influence on useful signal we have to create complex structures, which can approximately be described with one diode (per line), three diodes, or more detailed schematics.
I would suggest to check our part
ESD5V3U4U-HDMI. The schematic in the datasheet shows, that you have 4 protection devices in one package, each one connected between one signal line and ground. Each of those diodes can also be replaced with more complex equivalent circuit.
Now if you look at somewhat similar part
ESD3V3U4ULC, you will see pretty much the same schematic as in the parts you named. It can be read as follows: there is one protection device (represented in circuit by Zener-diode), and a steering array connecting all signals to it. If you compare function to the circuit above, it's virtually the same.
Best regards,
Anton Gutsul
