This is definitely an enterprise hardware question. You'll want to head on over to https://community.meraki.com/ for future enterprise questions and hopefully get a speedier response.
I don't believe what you are seeing is anything hampering your network or having a negative impact. It sounds like a combination of how client devices are tracked and the last device to send information.
In a track by MAC network, a layer 3 switch will send all data from 1 mac address. Depending on which IP it was sent from is the last one you will see reported in the clients list. Is your MS350 performing routing, and is your dashboard network set up to track client by. MAC address?