Currently, especially in the case of a parent with multiple children, the same group event will show up on a parents calendar twice is the children are in the same group. This also happens to a user who is the member of multiple groups where the same event is published. While the filter can assist in cluttering it is an all or nothing filter removing the events that don't appear twice (or more) as well. It would be useful if calendar views recognized the event was one event published to multiple groups.