Related answers to the same question could be displayed while you are answering a community wiki question.
This would encourage collaboratively improving (if needed) a very similar answer, instead of adding something which may be a duplicate.
If you are asking and answering a question in which you would potentially have a list of related questions and answers to look through to make sure you are not duplicating...your bigger concern should be about the fact that you are duplicating info and not that the information is not immediately available.
If someone is asking a question similar to another and the answer is something that is likely to be the same answer as the previous question, you likely have yourself a duplicate and it should be closed instead of answered.
I don't see what the point of differentiating CW questions is for.