Record duplication

Hello,
Please each time i click the botton (btn1) the record is added twice in my table.

Imports System.Data.OleDb
Public Class Form1

Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click
Try
Dim myConnection As OleDbConnection
Dim myCommand As OleDbCommand
Dim mySQLString As String
myConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\prog3\insert_form\Database5.mdb;")
myConnection.Open()
mySQLString = mySQLString = "INSERT INTO myuser (username, passwords) VALUES('" & txtid.Text & "','" & txtpw.Text & "')"
myCommand = New OleDbCommand(mySQLString, myConnection)
myCommand.ExecuteNonQuery()
myCommand = New OleDbCommand(mySQLString, myConnection)
myCommand.ExecuteNonQuery()
Catch ex As Exception
MessageBox.Show(ex.Message & " - " & ex.Source)
End Try
MessageBox.Show("Record Added Successfuly")
txtid.Text = ""
txtpw.Text = ""
End Sub
End Class