JPA Hibernate two entities with the same name, always saving in the same entity

Question

I have a jCombobox where all the entidades students. It happens to have two entities with the same name (two students Rodrigo Silva for example). Both are loaded on combo.

To the gravar the data in banco, no matter which one entidades listed with the same name I choose, is always recorded to the id lower (in this case the id 1). What I’m doing wrong, how can I fix this?

public T save(T t) throws Exception {
EntityManager em = getEm();
try {
    em.getTransaction().begin();
    if (t.getId() == null) {
        em.persist(t);

    } else {
        if (em.contains(t)) {
            if (em.find(t.getClass(), t.getId()) == null) {
                throw new Exception("Erro");
            }
        }
        t = em.merge(t);

    }
    em.getTransaction().commit();
} finally {
    em.close();
}
return t;

}

    ocorrencia.setAluno((Aluno) jCAluno.getSelectedItem());
    OcorrenciaDao oc = new OcorrenciaDao();
    oc.save(ocorrencia);

Method that populates the combo:

  public void loadComboAluno() {
    AutoCompleteDecorator.decorate(this.jCAluno);
    AlunoDao alunoDao = new AlunoDao();
    List<Aluno> listaAlunos = alunoDao.consultarAlunos();
    for (Aluno set : listaAlunos) {
        jCAluno.addItem(set);
    }
}

Consultation method:

   public List<Aluno> consultarAlunos() {
    EntityManager em = getEm();
    List<Aluno> listaAlunos;
    try {
        Query q = em.createNamedQuery("Aluno.findAll");
        listaAlunos = q.getResultList();
    } catch (Exception e) {
        listaAlunos = new ArrayList<>();

    } finally {
        em.close();

    }
    return listaAlunos;

}

Pupil Class:

    @Entity
@DynamicUpdate(value=true)
@NamedQueries({
    @NamedQuery(name = "Aluno.findAll", query = "SELECT c FROM Aluno c"),
    @NamedQuery(name = "Aluno.findByAlunoId", query = "SELECT c FROM Aluno c WHERE c.id = :id"),
    @NamedQuery(name = "Aluno.findByAlunoNome", query = "SELECT c FROM Aluno c WHERE c.nome = :nome")})
public class Aluno implements EntidadeBase, Serializable {

    @Id

    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "idAluno")
    private Integer id;
    @Column(name = "nomeAluno")
    private String nome;