Two jurists reach the same ruling in one case but offer different causes: one proposes factor A and the other factor B. A new case has A but not B. It does not follow that both jurists would agree on the new case.
Agreement on the ruling differs from agreement on the cause. Agreement on an original case does not guarantee identical reasoning for every new branch.
This connects composite consensus with analogy: the legal result cannot be transported to a new case without examining the operative cause and any relevant impediments.