Sometimes a question may (intentionally or unintentionally) be answerable in two parts, and sometimes said question may indeed be answered correctly by two different users, each answering a different part. How do we deal with this issue without seeming to prefer one answerer over the other?
The Accepted Answer is the post that best helped resolve your question. The best course of action is to accept one of the answers by whatever criteria you choose, then leave a polite, thankful comment in the other answer explaining that you also used their information and had considered accepting it. Don't forget to up-vote, too. They'll appreciate the affirmation.
If their answer are not complete, you can also create your own complete answer and accept it. You won't get any rep from it nor will your answer get bumped to the top as a normal accepter answer would be, so I really don't think this is cheating