registros duplicados

[Investment]

  //EVITAR DUPLICADOS
  if Tb1.locate('Cod1',Clave,[locaseinsensitive]) then
	ShowMessage('Ya existe la clave')
  else
	if Tb2.locate('Cod1',Clave2,[locaseinsensitive]) then
	  ShowMessage('Ya existe la clave2')
	else
	begin
	  Tb1.Insert;
	  Tb1.FieldByName('cod1').AsString := Clave;
	  Tb1.FieldByName('cod2').AsString := clave2;
	  Tb1.Post;
	  Tb1.Next;
	  Tb1.FlushBuffers;
	  Tb1Close;

	  Tb2.Insert;
	  Tb2.FieldByName('cod2').AsString := Clave2;
	  Tb2.FieldByName('des').AsString := clave4;
	  Tb2.post;
	  Tb2.Next;
	  Tb2.FlushBuffers;
	  Tb2.Close;

	  ShowMessage('LOS DATOS FUERON GRABADOS SATISFACTORIAMENTE!!');
	end;