请教

Question

下面程序是一个数据输入程序，为何每次输入后，显示两条纪录（但是打开数据库只有一条纪录）
unit Unit6;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DBCtrls, Buttons, Grids, DBGrids, ComCtrls, ToolWin,
  Mask, ExtCtrls;type
  Tform6 = class(TForm)
    ToolBar1: TToolBar;
    DBNavigator1: TDBNavigator;
    BitBtn1: TBitBtn;
    BitBtn2: TBitBtn;
    Label1: TLabel;
    Label2: TLabel;
    DBEdit1: TDBEdit;
    DBEdit2: TDBEdit;
    DBGrid1: TDBGrid;
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormActivate(Sender: TObject);
    procedure BitBtn1Click(Sender: TObject);
    procedure BitBtn2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
   private
    { Private declarations }
  public
    { Public declarations }
  end;var
  form6: Tform6;implementationuses unit2;
{$R *.dfm}
procedure Tform6.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  { datamodule2.bumentable.CancelUpdates;
   datamodule2.bumentable.Active:=false;  }
   action:=cafree;
   datamodule2.bumentable.close;
end;
procedure Tform6.FormActivate(Sender: TObject);
begin
   datamodule2.bumentable.Active:=true;
   datamodule2.bumentable.CachedUpdates:=true;
end;procedure Tform6.BitBtn1Click(Sender: TObject);
begin
    datamodule2.bumentable.applyupdates;
    {datamodule2.bumentable.CachedUpdates:=false; }
end;procedure Tform6.BitBtn2Click(Sender: TObject);
begin
   datamodule2.bumentable.cancelupdates;
   datamodule2.bumentable.CachedUpdates:=false;
end;procedure Tform6.FormCreate(Sender: TObject);
begin
  with datamodule2.bumentable do
  begin
     databasename:='laobao';
     tablename:='bumen.db';
{     indexfieldnames:='bumenname'; }
  end;
end;end.