Q: This system is labeled as "expandable". Does that mean the transmitter has the capability to communicate with two receivers simultaneously?

Yes, the transmitter is capable of broadcasting to 2 receivers simultaneously, when adding a 2nd receiver unit (part # CE-H22U11-S1, sold separately). Please note the transmitter acts as an extender/splitter, showing the same content on both displays, when a 2nd receiver unit is added