You can add a row to the list on the right without adding a row to the list on the left.
When you use the List command, you can have more than one list on a worksheet. You can add or delete a row in one list without adding or deleting a row in a list next to it, an ability new in Excel 2003.
You can also sort those lists separately, because using the List command automatically gives each list its own AutoFilter arrows. In previous versions of Excel, you could have AutoFilter arrows in only one list at a time. In Excel 2003, the AutoFilter arrows for each list are activated when you click inside that list.
Note, however, that if you have two lists side by side and you filter one of the lists, the other list will look filtered as well, because AutoFilter hides the entire row, not just the row in the list that is filtered.