danjc
Our database shows two notifications for group invitations. It looks like you are a member of one of the two groups already, so you have accepted the invitation. Is it possible you declined membership in the second? Or if you had accepted, you could have been removed from the group by the owner. Once an invitation is accepted or declined, it is removed from your pending invitations.
In any event, perhaps you can ask the group owner to invite you again. If you experience the same trouble, perhaps you can work with the group owner to document the workflow so that we might troubleshoot this further.
Thanks,
Mike