The whole idea behind the stack network is to generate multiple answers such that the best is voted to the top.
Having said that, Remi.b's answer is indeed somewhat of a duplicate answer. But in this case, given the question is kind of a facts question, generating a second answer can only be realized by duping prior ones, as the only correct answer is 85% = ORF = protein -- 15% = regulatory. If another users wishes to add another answer, it can't be left out or substituted because then the answer is incorrect. The only thing that can be added are additional sources (that's what Remi.b did) or add additional information, backgrounds or images.
In all, I think the answer is kind of a dupe, but reasonable given the type of question.
Of course they could have opted to comment below yours to generate a better answer out of yours, but that's not a hard rule.