The presence of a down arrow to the right of the name of an Agility contact indicates that the person works or writes for several publications.
If you would prefer to reach them via another one of their outlets, check the tick box next to their name to make sure they are selected. Then click on the arrow to show all of the outlets with which they are associated.
From here, select the radio button next to the outlet you wish to use for your list. You can then add them to a list using either the orange person icon, the Lists tool, or the ACTIONS button. When you go to the list, you will see that they have been added under the outlet that you selected earlier. Agility will always default to send communications to them at their preferred primary email address, but they will show up in your lists and any distribution reports according to the outlet that you prefer to see them associated with.