This can be achieved with a simple left join in the data sources tab. Inner would also work but you must be confident that all of the addresses also appear in CSV 2.
I've attached an example.
Simple CSV.twbx 14.2 KB
To achieve this you will have to "Join" your data.
1) After you connect to your first database (CSV 1) you should get a screen that looks like this:
2) Then go into "Add" and select you CSV 2 file.
3) Drag your CSV 2 worksheet into the pane, to the right of your CSV 1 and you should get a view that looks like this:
4) Now you will have to select the type of join you want. In your case an inner join by IP Address should work. If you have questions about how Joins work, you can read my blogpost about it here.
I hope this solves your answer. If you have any doubts do not hesitate on letting me know.