What is the ruling on someone who fed more than ten poor people out of doubt that there might be a previous oath he broke, of which he is unaware, and does the reward for both the intended and unintended feeding count?

If there is doubt about the validity of the oath, then feeding the poor is not sufficient if it becomes clear that another expiation is due from him. However, if the doubt is about breaking the oath, then this feeding is sufficient with the intention of expiation for the other oath, and expiating before breaking the oath is permissible. In the event that it is not sufficient, please write for him a charity.