You need to realize that if a field is already present in the select it could be that it is added with a 1 at the end. You normally want to rename those fields in your sql with "as".
Show the sql for both instances and we can tell you if that's the case.
Also, you can check with a sql manager what the resulting fields are really called.
Does it really say ADDRESSLN1?
Or you are working with static fields defined in the tdataset (which I would advice against).