[ecfisa]

Hola bulc.

La cantidad de imágenes involucradas, no me genera ningún tipo de problema. En este ejemplo uso 24 imágenes:

Código Delphi [-]
...
implementation

var
  vImage : array of TImage;

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  SetLength(vImage, 24);
  for i := 0 to ImageList1.Count-1 do
  begin
    vImage[i] := TImage(FindComponent('Image'+IntToStr(i+1)));
    vImage[i].Picture.Bitmap.Width  := 32;
    vImage[i].Picture.Bitmap.Height := 32;
    ImageList1.GetBitmap(i, vImage[i].Picture.Bitmap );
  end;
  Randomize;
end;

procedure TForm1.btnMergeClick(Sender: TObject);
var
  a,b,i: Integer;
  p: TPoint;
begin
  for i := Low(vImage) to High(vImage) do
  begin
    a   := Random(24);
    b   := Random(24);
    p.X := vImage[a].Left;
    p.Y := vImage[a].Top;
    vImage[a].Left := vImage[b].Left;
    vImage[a].Top  := vImage[b].Top;
    vImage[b].Left := p.X;
    vImage[b].Top  := p.Y;
  end;
end;

Salida:


Saludos