Is there a quick way to add bunch of admin accounts to 20+ Windows 2012 servers?
It would be way too cumbersome to rdp to each server and add accounts to the local admin group.
If these systems are members of an Active Directory domain you can use group policy to add a group of admin users to the Local Administrators group.
If these systems are members of a domain but the users are local, you can use Restricted Groups to produce the desired effect.
If these computers are not members of an AD domain you can use PowerShell to connect to the systems and adjust the group memberships.