if Source = ImageEnMView2 then
    begin
     idx := ImageEnMView2.SelectedImage; // <-- this is issue
   //uses whatever image highlighted as selected, clicking and
  //dragging right away, causes this to give bad 
  // results by moving the wrong image.

     im  := ImageEnMView2.InsertingPoint(X, Y);
     if (idx > -1) and (im > -1)
      and (im <= ImageEnMView2.ImageCount)
       and (idx <= ImageEnMView2.ImageCount)
       then
        begin
         ImageEnMView2.MoveSelectedImagesTo(im);
         ImageEnMView2.IEEndDrag;
         ImageEnMView2.Update;
        end;
    end;

procedure TForm1.ImageEnMView1DragDrop(Sender, Source: TObject; X, Y: Integer);
var
  iIndex: integer;
begin
  ImageEnMView1.MultiSelectSortList; // selection order is not important
  iIndex := ImageEnMView1.InsertingPoint(X, Y);
  ImageEnMView1.MoveSelectedImagesTo(iIndex);
end;

procedure TForm1.ImageEnMView1DragOver(Sender, Source: TObject; X, Y: Integer; State: TDragState;
  var Accept: Boolean);
var
  iIndex: integer;
  imgX, imgY: integer;
begin
  if Source = ImageEnMView1 then
  begin
    Accept := True;
    iIndex := ImageEnMView1.InsertingPoint(x, y);
    imgX := ImageEnMView1.ImageX[iIndex] - ImageEnMView1.ViewX;
    imgY := ImageEnMView1.ImageY[iIndex] - ImageEnMView1.ViewY;
    ImageEnMView1.Paint;
    // draw a horzontal red line to show the insertion point
    with ImageEnMView1.GetCanvas do
    begin
      Pen.Color := clRed;
      Pen.Width := ImageEnMView1.SelectionWidth;
      MoveTo(imgX + 10, imgY);
      LineTo(imgX + ImageEnMView1.ThumbWidth - 10, imgY);
    end;
  end;
end;

procedure TForm1.ImageEnMView1EndDrag(Sender, Target: TObject; X, Y: Integer);
begin
  // stop dragging
  ImageEnMView1.IEEndDrag;
  ImageEnMView1.MouseInteract := [mmiSelect];
end;

procedure TForm1.ImageEnMView1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
  if (ssLeft in Shift) then
  begin
    ImageEnMView1.MouseInteract := [];
    // initiate dragging
    ImageEnMView1.IEBeginDrag(true, -1);
  end;
wnd;