I have no idea if C-Mores will do this, but it's common with with many brands for multiple HMI's to have one be the master, and all the others request their data from that one, then it bundles all the data required and gets it all from the PLC in one shot. That makes the PLC comms more efficient, avoids redundant requests, plus avoiding the potential for collisions between requests from HMI's all acting as comm masters.