I am sending you my passport with my picture on it. Why do you need another 2×2 photograph for the visa application?
When the Consulate receives both, it is easier for them see that the person who is applying for the visa and the person on the passport are the same. Also, U.S. passport is usually valid for 10 years and within that timeframe, people’s appearance tends to change. Providing the most recent passport style photograph on the visa application is the best way for the Consulate to keep track of your appearance when you enter the country.