Battlestar Galactica bluray series question...no spoilers!

[Sinclair]

So a few weeks ago I went to Best Buy and purchased all the seasons on bluray for $20 apiece (1,2,3,4,&4.5). I just started season 4 with the Razor movie. My question is do I even need season 4.5? I haven't opened it yet but season 4 seems to have everything plus 4.5. I want to take it back if I'm not gonna need it and I figure someone here could help me out.

By the way I'm really loving the series!!!