It's easy to benchmark.

• Use your dual core computer, set up a Poser scene (any scene).

• Before rendering, fire up the task manager, and set the "CPU affinity" setting of Poser to only one core (Process tab, right click on Poser). That way it only can use one core, because Windows won't give access to the other one.

• Render.

• Then check back the affinity for both cores, render again.

Compare times.