As muttbarker has said, you will need to use Host Checker. If this is a machine you have control over initially, you can do registry/MAC/NetBIOS/etc. Another option is to use the "file" check; you would put a file somewhere on the system, preferably as hidden as possible, and check for this in the policy and set the behavior to deny. And make sure to not list the reason string for users if they fail.
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