Mac Agent shows incorrect Computer Name (machine id) after checking in? 

You have used agent package to set it to be a different name but once the agent checks in the machine name is not what you have configured it to be.

Read this article for the solution: 

https://helpdesk.kaseya.com/hc/en-gb/articles/229039308-Mac-Agent-shows-incorrect-Computer-Name-machine-id-after-checking-in