When you are adding a user, you may find that the user has a duplicate entry. The name and email address will be the same, and it is difficult to know which one to select.
To find the most recent entry, Select GEANT from the left hand sidebar, and Members
Search for the name or email address of the user. You will see the duplicate entries and note that they have different federated-user-ID's
The most recent entry can be found by selected the higher number from the ID column - in this case 8162.