Leibniz and Newton are usually considered as the inventors of calculus. During the 17th century, a huge controversy disrupted the scientific world. In fact, for their contemporaries, it was not clear who invented calculus between Leibniz and Newton. And most importantly, the question was "who has copied who". Nowadays, there is no longer dispute about this. Thanks to their manuscripts, we know that their approaches were totally different and that no one has copied the other. But still, this dispute generated great tensions during decades. In this essay we cover their discoveries, compare their dispute with the one between Tartaglia and Cardanno-Ferrari and elucidate an extract from 'The History of Mathematics, a very short introduction' written by Jacqueline Stedall on this topic. We will more about the characteristics of a mathematical dispute and also the role of mathematical historian.