Likewise, negation can happen in either antecedent or consequent to enhance the hypotheticality, (12)a with double affirmative can be interpreted either as a CF or as a non-CF, while the general reading of (12)b is only a CF.
both of them don't entail the counterfactuality , which can be cancelled by introducing an additional clause preceding them, like "我不知道你刚才有没有来这/ 叫住他，但是……(I don't know whether you were here / stopped him just now, but…)".