I think you may find MZM with single drive or two drives,In single drive both phase shift arms are connected to the same voltage and for two or dual drives,two phase shift arms are connected to different voltage source.
I think ,the dual electrode is two voltage drive.
Single voltage drive may be used only for phase shift but two dual drive may be for phase and amplitude modulation.
check the help of the component in “Transmitter lib./Modulators/Optical”