If all the devices are registering as the same device, it suggests there could be something unsupported/strange with the deployment method.
Are you pre-installing the SM agent into an image and then deploying that image to other device? Or, are you using VMs for this, where the UUIDs/Serials might be shared between multiple clients? Either way, open a support case and Meraki Support can help you resolve it further, but those are the two most common reasons for devices to be enrolling as the same client. @JMCCSDA