Note that Windows allows for duplicate domain and local users; this is why users get prefixed by the domain or local machine name. Comparing the output of whoami and hostname will reveal if you’re logged in with a local or domain account.

Remember that net group $GROUP /domain doesn’t show which domain groups are members of $GROUP, and thus will miss domain admins whose membership is controlled by a nested group. The only way to retrieve a full list of users in a domain group is to use PowerShell.