Wouldn&rsquo;t you like to be a Pepper, too? That won&rsquo;t be happening for aspiring soda-making rivals anytime soon, because another soft drink with a famously secret formula is Dr Pepper, which is made from 23 natural and artificial flavors. &nbsp;Only three people are said to be privy to the recipe, which was invented in 1885 by pharmacist Charles Alderton in Waco, Texas, and is kept locked in a vault in company headquarters in nearby Plano. The company has gone  to deny one common guess at ingredients: th