calendar appointment going to multiple users when calendars are shared

This is with outlook 2010. User 1 has a shared calendar with user 2 and 3. User 2 has his calendar shared with users 1,3,4,5. User 1 went into the calendar, and sent an invite to an appointment only to user 2 and 3.. This invite went out to all the users when it should have just went to 2 and 3. Any thoughts?