Yes, I agree that it's important to debunk these myths. There may be some cases where people are motivated to believe myths even when they know they are not factually accurate, but education can be helpful in many other cases. A fellow PT blogger wrote a post debunking the rape-pregnancy myth here: http://www.psychologytoday.com/blog/animals-and-us/201208/why-are-rape-victims-more-not-less-likely-become-pregnant
Also see these sources for more debunking:
http://www.d.umn.edu/cla/faculty/jhamlin/3925/myths.html
http://www.huffingtonpost.com/soraya-chemaly/50-facts-rape_b_2019338.html