Yes I do wonder if it could be a mix up. I don't know whether the 1861 enumerators took details verbally (in which case he could quite easily have mixed up the mother and daughter's names) or if the householder filled out a form like in 1911 (in which case it would have been harder to mix them up). I just wondered if
Jemima and
Sarah were 2 versions of the same name - sort of like
Elizabeth and
Betty.