Quote - Ponder this: If you have a 64-bit OS and are installing the 64-bit Poser, why would they bother to ask you if you want to install the 32-bit as well? What possible advantage could there be to having both? Might it be because the 32-bit version, despite being unable to use all your RAM, is faster for some scenes?

One of the reasons is that (according to the product info at CP) some of the Poser Fusion plugins are 32-bit only.