Redundant Information.

Very rarely will a GMAT question waste even a SINGLE word. Every questions has been maticulously created to make sure there is 100% clarity, no confusion, and only 1 correct answer. GMAC estimates that it costs over $2500 to create EACH question. So it is my guess that you are either looking at a poorly written practice question (not from GMAC) or you are missing something in the question. Can you post the question you are curious about? Even single words can make HUGE differences in questions. Think about words such as "positive, even, integer, nonzero, greater than, etc...". Every word has been put in there for a very specific reason!

Just remember, if you see anything in a question that looks fishy, or you see some type of pattern/redundancy, it has most likely been put there for a reason. Use that as a sort of "hint" that will help you figure out how to solve the question and eventually get you to the correct answer.