两个不同的组合框在其中一个更改时显示相同的值

c# 在visual studio中,我有两个 combobox 命名1) senderReferringComboBox recieverReferringComboBox 我正在填充这两个 comboBox

   DataSet myDataSet = new DataSet();
   string sql = " Select dbo.Position.ID, dbo.Position.usr_Id as UserId, dbo.Position.Title + ' (' + dbo._User.LastName + ' ' + dbo._User.FirstName + ')' AS UserPosition" +
                " FROM  dbo._User INNER JOIN " +
                " dbo.Position ON dbo._User.ID = dbo.Position.usr_Id " +
                " WHERE (dbo._User.IsActive = 1) and dbo._User.Id !=" + UIHelper.CurrentUser.Id +
                " ORDER BY dbo.Position.Title";

   DataTable table = client.GetDataTable(null, sql, null);
   myDataSet.Tables.Add(table);

   DataView dvw1 = myDataSet.Tables[0].DefaultView;
   DataView dvw2 = myDataSet.Tables[0].DefaultView;

   senderReferringComboBox.DataSource = dvw1;
   senderReferringComboBox.DisplayMember = "UserPosition";
   senderReferringComboBox.ValueMember = "UserId";
   senderReferringComboBox.SelectedIndex = -1;

   recieverReferringComboBox.DataSource = dvw2;
   recieverReferringComboBox.DisplayMember = "UserPosition";
   recieverReferringComboBox.ValueMember = "UserId";
   recieverReferringComboBox.SelectedIndex = -1;  

当我在中更改值时 senderReferringCombox 接收引用组合框 . 我有两种不同的观点?为什么会这样?我怎样才能预防呢?