So you can see whether or not the keyword has been added to one folder (or client), and not another. Either the ability to hover over the check mark next to the keyword and it will list the folders it is a part of, or the ability to filter out the entire keyword results (contained in X folder, not contained in X folder).
OR the ability to drill into a specific client folder where you are only doing keyword research for them.
i.e. I am doing kw research for my finance client. I don't want to see the keywords that are marked as added for my fitness client when doing kw research.