Thanks to Alpha for the heads up.
Thought you might want to post up the US versions of the Season 1 & 2 Blu-ray sets. I took various shots, including one with all four. They altered the side of the Blu-ray case for 1 & 2, and there's a comparison shot between 1 and 4 that shows the difference. I saw the post with the Blu-ray sets from Region 2 (I think), but these are the ones from the US. Hope they help.
Pictures:
Season 1/2:
Season 1 Discs:
Season 2 Discs:
Season 1 - Season 4 (Blu-ray):
Comparison - side of case (Season 1 on top, Season 4 on the bottom):