One listener asks, “Is he really coming? I am not sure.” Another declares, “That is wrong; he will not come.” These are different states of mind.
The first shows hesitation: the hearer has not settled the issue. The second shows denial: the hearer rejects the claim.
One emphatic marker may be sufficient for hesitation, whereas denial may require stronger reinforcement proportionate to its intensity. Ignoring that distinction can make an otherwise correct sentence rhetorically ill suited.