public void ValidCiticenDuplicate() { foreach (ExamFileDetail detail in ExamFileDetails) { IEnumerable <ExamFileDetail> ExamDetails = this.ExamFileDetails.Where(a => a.ID_CARD_NO == detail.ID_CARD_NO); if (ExamDetails.Count() > 1) { //this.DuplicateCitizen(); foreach (ExamFileDetail Exam in ExamDetails) { Exam.DuplicateCitizen(); } } } }