If two exact models of martingales are used such as: n1 = 1,2,3,4,5,6,7 and n2 = 1,2,3,4,5,6,7

While flipping a two sided coin, heads and tails, where each martingale has 7 tries.

What is the probability that using a coin toss, both martingales will land all heads back to back every time.

For example, while flipping a coin, each chance is 50% each and every time, however would the odds of both martingales flipping heads all 14 times in a row, be less than 50%? (total of 14 flips in a row because the problem uses two martingales with 7 flips each)

Thanks.