From the Epi site:

...With your choice of either 1/4" mono output blending both pickups or 1/4" stereo output splitting the two pickups, you have incredible flexibility and opportunities to create the perfect acoustic tone live!......

I see what you mean. It appears it doesn't have a blender control on the pre-amp so that when you're using the mono jack you're always going to have a blend of both pickups. That might be it's best sound though and therefore not a problem.

The nice thing about the stereo output is you can run the bridge to a full range system, the neck to a regular guitar amp, and get a wide range of sounds at your disposal. I had that on my Parker Event.