ติด error A column named 'item' already belongs to this DataTable แก้ยังไงค่ะ

Imports System.Data.SqlClient
Public Class frmremedy_Medi
    Dim dtRemedy As DataTable = New DataTable("Dt_Order")
    Dim flagClear As Integer = 0

    Private Sub frmremedy_Medi_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        LoadData()
    End Sub

    Sub LoadData()
        Dim connect As SqlConnection = New SqlConnection("Data Source=(local)\SQLEXPRESS;Initial Catalog=Clinic;Integrated Security=True")
        Dim sql As String = "SELECT max(Reme_Number) as MaxReme from Remedies"
        Dim sqlCmd As SqlCommand = New SqlCommand(sql, connect)
        connect.Open()
        Dim reader As SqlDataReader = sqlCmd.ExecuteReader()
        reader.Read()

        Dim RemNum As String
        RemNum = reader("MaxReme").ToString()
        reader.Close()
        Dim RemeMax As Integer

        If RemNum = "" Then
            RemeMax = 1
        Else
            RemeMax = CInt(RemNum) + 1
        End If

        If RemeMax < 10 Then
            txtRemSearch.Text = "0000" + RemeMax.ToString()
        ElseIf RemeMax >= 10 And RemeMax <= 99 Then
            txtRemSearch.Text = "000" + RemeMax.ToString()
        ElseIf RemeMax = 100 And RemeMax <= 999 Then
            txtRemSearch.Text = "00" + RemeMax.ToString()
        ElseIf RemeMax >= 1000 And RemeMax <= 9999 Then
            txtRemSearch.Text = "o" + RemeMax.ToString()
        Else
            txtRemSearch.Text = RemeMax.ToString()

        End If
        txtRemeDate.Text = Date.Now().Date

        'ดึงข้อมูลจากตารางยามาแสดง()
        Dim Sql2 As String = "SELECT Medi_ID,Medi_Name from Medicines"
        Dim Sqlcmd2 As SqlCommand = New SqlCommand(Sql2, connect)
        Dim Sqladp As SqlDataAdapter = New SqlDataAdapter(Sqlcmd2)

        Dim ds As DataSet = New DataSet()
        Sqladp.Fill(ds, "medi")

        cboMedi.DataSource = ds.Tables("medi")
        cboMedi.ValueMember = "Medi_ID"
        cboMedi.DisplayMember = "Medi_Name"

        'ดึงข้อมูลจากตารางโรคมาแสดง

        Dim Sql3 As String = "SELECT Dise_ID,Dise_Name from Diseases"
        Dim Sqlcmd3 As SqlCommand = New SqlCommand(Sql3, connect)
        Dim Sqladp2 As SqlDataAdapter = New SqlDataAdapter(Sqlcmd3)

        Dim ds2 As DataSet = New DataSet()
        Sqladp2.Fill(ds2, "Dise")

        cboDise.DataSource = ds2.Tables("Dise")
        cboDise.ValueMember = "Dise_ID"
        cboDise.DisplayMember = "Dise_Name"

        

        connect.Close()


        If flagClear = 0 Then

           dtRemedy.Columns.Add("Medi_ID")'บรรทัดนี้เเลย
            dtRemedy.Columns.Add("Medi_Name")
            dtRemedy.Columns.Add("qty")
            dtRemedy.Columns.Add("Total")

        End If
        '        Dim DiseTotal As Double = CDbl(txtDisePrice.Text)
        '        txtTotal.Text = DiseTotal.ToString()
    End Sub
    'ต้องการให้กดค้นหาแล้วขึ้นdialog
    Private Sub btnPat_Search_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPat_Search.Click

        PatIdSearch = txtPat_IDSearch.Text
        lovPat.ShowDialog()

        Dim connect As SqlConnection = New SqlConnection("Data Source=(local)\SQLEXPRESS;Initial Catalog=Clinic;Integrated Security=True")
        Dim sql As String = "select* from Patients where Pat_ID = '" + PatIdSelect + "'"
        Dim sqlCmd As SqlCommand = New SqlCommand(sql, connect)
        connect.Open()
        Dim reader As SqlDataReader = sqlCmd.ExecuteReader()
        reader.Read()

        If (reader.HasRows) Then
            txtPat_IDSearch.Text = PatIdSelect
            txtFName.Text = reader("Pat_FName").ToString()
            txtLName.Text = reader("Pat_LName").ToString()
            maskTel.Text = reader("Pat_Phone").ToString()
            txtPat_Address.Text = reader("Pat_Address").ToString()
        End If

        reader.Close()
        connect.Close()

    End Sub
    'แสดงราคาต่อหน่วยและยาในคลังอัตโนมัติ ที่เลือกจากcombobox
    Private Sub cboMedi_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboMedi.SelectedIndexChanged
        Dim Medi As String = cboMedi.SelectedValue.ToString()
        Dim connect As SqlConnection = New SqlConnection("Data Source=(local)\SQLEXPRESS;Initial Catalog=Clinic;Integrated Security=True")

        Dim SqlString As String = "Select Medi_QtyOnHand,Medi_SalePrice from Medicines where Medi_ID = '" + Medi + "'"
        Dim sqlCmd As SqlCommand = New SqlCommand(SqlString, connect)
        connect.Open()

        Dim reader As SqlDataReader = sqlCmd.ExecuteReader()
        reader.Read()


        If (reader.HasRows) Then
            txtOnHand.Text = reader("Medi_QtyOnHand").ToString
            txtunitPrice.Text = reader("Medi_SalePrice").ToString

        End If
        reader.Close()
        connect.Close()
    End Sub
    '    'ค่ารักษาโรค
    Private Sub cboDise_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboDise.SelectedIndexChanged
        Dim Dise As String = cboDise.SelectedValue.ToString()
        Dim connect As SqlConnection = New SqlConnection("Data Source=(local)\SQLEXPRESS;Initial Catalog=Clinic;Integrated Security=True")

        Dim SqlString As String = "Select Dise_Price from Diseases where Dise_ID = '" + Dise + "'"
        Dim sqlCmd As SqlCommand = New SqlCommand(SqlString, connect)
        connect.Open()

        Dim reader As SqlDataReader = sqlCmd.ExecuteReader()
        reader.Read()


        If (reader.HasRows) Then
            txtDisePrice.Text = reader("Dise_Price").ToString

        End If

        reader.Close()
        connect.Close()
    End Sub
    'ปุ่มสั่งซื้อ
    Private Sub btnOrder_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOrder.Click
        Dim ID As String = cboMedi.SelectedValue.ToString()
        Dim name As String = cboMedi.Text.ToString()
        Dim qty As Integer = CInt(txtUnit.Text)
        Dim Price As Double = CDbl(txtunitPrice.Text)
        Dim PriceItem As Double = qty * Price

        Dim drNew As DataRow
        drNew = dtRemedy.NewRow()
        drNew("Medi_ID") = ID
        drNew("Medi_Name") = name
        drNew("qty") = qty
        drNew("Total") = PriceItem

        dtRemedy.Rows.Add(drNew)
        dgvRemedy.DataSource = dtRemedy

        ShowTotalAmount()
    End Sub
    'คำนวนราคาสินค้ารวมโดยใช้ForLoop
    Sub ShowToTalAmount()

        Dim sumTotal As Double
        Dim dr As DataRow

        For Each dr In dtRemedy.Rows

            sumTotal = sumTotal + CDbl(dr("Total"))

        Next
        Dim DiseTotal As Double = CDbl(txtDisePrice.Text)
        txtTotal.Text = (DiseTotal + sumTotal).ToString()
    End Sub
   
    'ปุ๋มบันทึกข้อมูล

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim RemeDy_Num As String = txtRemSearch.Text
        Dim Pat_ID As String = txtPat_IDSearch.Text
        Dim Dise_ID As String = cboDise.SelectedValue

        Dim day As String = Date.Now().Date.Day
        Dim month As String = Date.Now.Date.Month
        Dim Year As String = Date.Now.Date.Year
        Dim RemeDate As String = month + "/" + day + "/" + Year

        Dim connect As SqlConnection = New SqlConnection("Data Source=(local)\SQLEXPRESS;Initial Catalog=Clinic;Integrated Security=True")
        Dim SqlIN As String = "InSert InTo Remedies(Reme_Number,Pat_ID,Remedy_Date) Values ('" + RemeDy_Num + "','" + Pat_ID + "','" + RemeDate + "')"
        Dim sqlCmd As SqlCommand = New SqlCommand(SqlIN, connect)
        connect.Open()
        Dim successInSert As Integer = sqlCmd.ExecuteNonQuery()




        Dim successInSert2 As Integer
        Dim sqlCmd2 As SqlCommand
        For i = 0 To dtRemedy.Rows.Count - 1

            sqlCmd2 = New SqlCommand("InSert InTo RemedyDetails(Dise_ID,Reme_Number,Medi_ID,OrderMediQty)Values('" + Dise_ID + "','" + RemeDy_Num + "','" + dtRemedy.Rows(i)("Medi_ID") + "','" + dtRemedy.Rows(i)("Qty") + "')", connect)

            successInSert2 = sqlCmd2.ExecuteNonQuery()
        Next



        If successInSert > 0 And successInSert2 > 0 Then
            MsgBox("บันทึกข้อมูลเรียบร้อย")
            'clearForm()
            LoadData()
        Else
            MsgBox("การบันทึกข้อมูลไม่สำเร็จ")
        End If
        connect.Close()



    End Sub
    'ลบค่าที่เลือกในดาต้าGrid
    Private Sub btndelet_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btndelet.Click
        Dim row As DataGridViewRow
        Dim NumRow As Integer = dgvRemedy.Rows.Count

        For A As Integer = 0 To NumRow

            For Each row In dgvRemedy.Rows

                If row.Selected Then
                    Dim rIndex As Integer = CInt(row.Index)
                    dgvRemedy.Rows.RemoveAt(rIndex)
                    ShowToTalAmount()

                End If

            Next
        Next



    End Sub
    Sub ClearForm()
        txtFName.Text = ""
        txtLName.Text = ""
        txtPat_Address.Text = ""
        maskTel.Text = ""
        txtPat_IDSearch.Text = ""
        txtUnit.Text = ""
        txtDisePrice.Text = ""
        txtOnHand.Text = ""
        txtTotal.Text = ""
        txtunitPrice.Text = ""

    End Sub
End Class