If someone makes an ahd not to raise his voice over his mother’s in wrangle (like long argumentation). Then he doubts whether he raised his voice or not or if he does raise slightly but in short argumentation or he does it due to forgetfulness – does he need to pay kaffarah? In that case is it sufficient to pay once?

If they know they raised their voice, even if forgetfully, then they should pay the kaffarahً that is necessary for breaking the ‘ahd (feeding 60 poor people).