In this case, there is not much to do other than validate each MX individually.
When I use templates, I always use the same MX model and use a standard set of ports to make management easier in these cases. Of course, it is not always possible to follow it exactly, depending on the location, but it helps a lot.
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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