Should there be a rule or at least understanding that something should not be said twice in a thread?

What I am talking about is when someone answers, then another answers with the same thing. I am referring to general questions, not opinion/social questions. It has happened to me a few times and what has also happened in those situations to augment the situation is that people give credit for the person who posted after me! I think that people should read the previous posts before posting their own, or at least control-f their answer so they get a fastpass to whether or not what they want to say has already been said. Do you think that this is just? Is there a rule already? Has it ever happened to you? I was just wondering…