How to Disable Single Sign-On in Windows 7 guests?

Our current configuration uses different passwords for the User Portal login and the Windows 7 login.

When the user starts the Spice client for the Windows 7 guest, it seems to try to log in.  This sometimes results in a screen saying that the user should press C-A-D to get back to the login screen.

Is there a way to disable Single Sign-On in the Windows 7 guest?