If someone response with an amen chatufa can he yotzei himself or motzei someone else by say an incorrect amen?
When being yotza with someone else’s bracha we should answer amen. However if we didn’t answer, we are still yotza the bracha b’dieved (if both the person saying and the person hearing the bracha had in mind that we should be included in the bracha). The reason for this is because we say “shomaya k’ona”, a person that is listening to something it is as if he himself actually said it. Therefore b’dieved he is still yotza.
Your question however is more complicated situation, because perhaps by saying the amen that was not supposed to be said, it would constitute a hefsek. This however is incorrect and it is not considered a hefsek. The reason is that although he wasn’t supposed to say the amen incorrectly, however his saying the amen was related to the meal or mitzvah that was being done, therefore b’dieved we do not say that it is considered a hefsek.
I don’t understand what you mean, when you wrote, “or motzei someone else by say an incorrect amen”, because we are not motzi someone else by saying amen.
O:CH 213-2 M:B 17.O:CH 167-6.