A similarity of both Atticus and Mrs. Dubose showing courage is when they both tackle an obstacle they know they will lose in the end. With Atticus, he is truly defending Tom Robinson and proving his innocence, but know that he will still be found guilty by the jury. With Mrs. Dubose, she was determined to overcome her morphine addiction before she died. She knew she was close to death and it was important to her to break the addiction, and in the end, she died. Both characters still put forth all their strength and effort knowing the end outcome would not be favorable.
However, even though Atticus technically lost the Tom Robinson case, he still 'won' in a sense. One juror held the jury out for hours because he believed in Tom Robinson's innocence. It was not a quick decision by the jury.