Last week G instituted a change. Previously, only one manager was allowed to access and manage an individual account through an MCC. As of last week, you can now have up to 2 managers for an individual account. The first manager get's the traditional web interface and API access and the second manager gets "api access only" access. Interesting. It avoids the issue for managers wherein your customer wants to work with two providers, or if you have an agency customer, the agency only wants to allow you, the provider, access to select accounts without losing access to those select accounts themselves.