Actually, if you ask 30 people, the probability is less than 8 percent.
P(X>=1) = 1 - (1-1/365)^30
It depends on whether any two people should share a birthday or any person with a certain one.

And 1/14,000,000 + 1/14,000,000 = 2/14,000,000 = 1/7,000,000 (That's exactly the way that most people understand the term of doubling)