As opposed to duel core support, in which case, I suppose one of the cores would win, and one would lose, leaving you with only one core.

However, if you are using a dual core optimizer in order to be able to run EQ2, you can disable it as EQ2 supports the multi-core CPUs now.

It doesn't really offload much to the second cpu though. Reading Autenil's blog, it only moves some of the animation work to the second processor, with the first one still doing the majority of the number crunching. Still, better than nothing.