According to this video, it is not even that rare, just in the USA there are 150 of them:
http://abcnews.go.com/blogs/health/2012/01/12/born-with-two-vaginas-not-so-rare/
"as I went into labor and interestingly the left cervix dilating even though the pregnancy was in the right womb,” wrote GA of East Sussex to the Daily Mail newspaper. ”How interesting is the human body?”
Indeed....
http://abcnews.go.com/blogs/health/2012/01/12/born-with-two-vaginas-not-so-rare/
"as I went into labor and interestingly the left cervix dilating even though the pregnancy was in the right womb,” wrote GA of East Sussex to the Daily Mail newspaper. ”How interesting is the human body?”
Indeed....