Insert data into a table with the same primary key

Good, I'm doing a screen where I store the payments of some clients, at the moment of inserting, I must put the same client code. I must use the same client id which is the primary key which gave me an error. I could fix it by doing a procedure but now it does not save anything and it does not return an error.

Here the procedure

ALter procedure SP_InsPagosMa3
    @CodigoCliente VARCHAR (10),
    @CodigoBanco VARCHAR(2),
    @MontoTotal float,
    @NumPago varchar(20),
    @FechaPago datetime,
    @FechaRegistro datetime

AS
BEGIN
INSERT INTO PagosManuales (CodigoCliente,CodigoBanco, MontoTotal, NumeroPago,FechaPago,FechaRegistro)
SELECT

     CodigoCliente = @CodigoCliente,
    CodigoBanco=@CodigoBanco,
    MontoTotal=@MontoTotal,
    NumeroPago=@NumPago,
    FechaPago=@FechaPago,
    FechaRegistro=@FechaRegistro

From [CobrosDirectos].[dbo].[PagosManuales]
 WHERE CodigoCliente = @CodigoCliente
END.

VB code of my function

Public Function IsnPago(ByVal CodigoCliente As String, ByVal CodigoBanco As String, ByVal MontoTotal As Double, ByVal NumPago As String, ByVal FechaPago As Date, ByVal FechaRegistro As Date) As String

    Dim cn As New Data.SqlClient.SqlConnection
    Dim cmd As New SqlCommand
    Dim Resultado As String
    cn.ConnectionString = C.GetAppConfiguracion("CobroDirecto", "ConnCobroDirecto")
    Dim Str As String
    Str = ""
    cn.Open()

    Str = "EXEC SP_InsPagosMa3 CodigoCliente,@CodigoBanco,@MontoTotal,@NumPago,@FechaPago,@FechaRegistro"


    cmd = New SqlCommand(Str, cn)
    With cmd
        .Parameters.Add("@CodigoCliente", Data.SqlDbType.VarChar, 10).Value = CodigoCliente
        .Parameters.Add("@CodigoBanco", Data.SqlDbType.VarChar, 2).Value = CodigoBanco
        .Parameters.Add("@MontoTotal", Data.SqlDbType.Float).Value = MontoTotal
        .Parameters.Add("@NumPago", Data.SqlDbType.VarChar, 20).Value = NumPago
        .Parameters.Add("@FechaPago", Data.SqlDbType.DateTime).Value = FechaPago
        .Parameters.Add("@FechaRegistro", Data.SqlDbType.DateTime).Value = FechaRegistro
        .ExecuteNonQuery()
    End With

    cn.Close()
    Resultado = "Pago aplicado"

    Return Resultado

End Function

Code of when I call her

protected Sub BtnAplica_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles BtnAplica.Click


    Dim resultado As String
    Dim Seleccion As Boolean = False
    For Each RW As GridViewRow In Gvcobranzas.Rows
        If CType(RW.Cells(2).FindControl("CheckBox1"), CheckBox).Checked Then
            resultado = GM.IsnPago(TxtBuscarCli.Text, dlBnaco.SelectedValue, TxtPagoTotal.Text, TxtNuPago.Text, TxtFePago.Text, TxtFeReg.Text)
            Seleccion = True
            With lberror
                .Visible = True
                .Text = resultado
            End With
        Else
            With lberror
                .Visible = True
                .Text = "Favor de seleccionar las factura a pagar"
            End With
        End If
    Next
    CargaGridClientes()





End Sub