In this mechanical scenario, the motor rollers are not coupled together as shown.
In ZPA Mode with this mechanical configuration, it because the module will never monitor and adjust the Slave Motor’s speed. Because they are un-coupled; both motors will vary their speed based upon their respective loads while the module is only paying attention to the load on the master.
PLC I/O Mode and ConveyLogix Program
You can set the motors to the same settings in EasyRoll and logically run both motors at the same time in your PLC logic program or ConveyLogix program. Even though you can attempt to use the Master/Slave functionality as previously described, you will have the same situation as just described for ZPA mode where uncoupled motors will vary their speed.