Jennifer,
No. Continue to save your alpha masks as 32 bit, or as a .png file. If you save them as a 24 bit file, the texture will be opaque and wont do you any good at all. The textures in question are those directly applied to the mesh clothing. As far as the 2 shirts being the same, well, they are essentially. The only difference is that one was saved at 32 bits ( the one showing the background thru my body) and the other was 24 bit.