Is there a reason to my second instantiated object takes my first object's value?

Question

When I insert a second Object(a Child), I need to assign to his parent the name of his child (having already the Child object, that has the parents name in a property), but when I call the Parent object always returns the child object.

I'm using a Hashtable to store "Cargo" objects.

// Hashtable(key,value)
TablaCargos(CargoObject.Name, CargoObject)

And every Cargo should have a Parent and a Child list

Part of my class Cargo

class Cargo {
  private string nombre;
  private string codigo;
  private string padre;
  private List<string> hijos = new List<string>();

  public Cargo() {
    nombre = "";
    codigo = "";
    padre = "";
    hijos = new List<string>();
  }

  //getter and setters
}

My form

Cargo cargo = new Cargo();
Cargo cargoHijo = new Cargo();
Cargo cargoPadre = new Cargo();
Hashtable TablaCargos = new Hashtable();
string Root = "";

private void btnAgregar_Click(object sender, EventArgs e)
{
  cargo.Nombre = txtNombre.Text;
  cargo.Codigo = txtCodigo.Text;
  cargo.Padre = txtPadre.Text;

  TablaCargos.Add(txtNombre.Text, cargo);

  Ordenamiento(txtNombre.Text);
}

private void Ordenamiento(string cargoActual) {

  cargoHijo = (Cargo)TablaCargos[cargoActual];

  if (cargoHijo.Padre == "") {
    // THIS IS A PARENT
    Root = cargoActual;
  } else {
    // THIS IS A CHILD
    AsignarPadre(cargoHijo.Padre, cargoHijo.Nombre);
}

private void AsignarPadre(String Padre, String Hijo)
{
  // THE PROBLEM IS HERE, CLEARLY I SEND THE Parent's KEY

  cargoPadre = (Cargo)TablaCargos[Padre];

  // BUT IN THE NEXT LINE cargoPadre TAKES THE VALUE OF THE CHILD
  // THE SAME VALUE OF cargoHijo

  cargoPadre.Hijos.Add(Hijo);
}

I expect to assign the child's name to the parent's child property, but the child takes it.

Maybe I miss an instantiation or, I don't know

Answer 1

The problem was solved with this line cargo = new Cargo(); at the beginning btnAdicionar_Click. Thank you all for your time and advice. :)