The easy answer is to either DIY one yourself (battery boxes aren't very complicated), or simply glue two UGLY-BBs together. That would give you separate ins and outs (and still use two batteries, providing some redundancy) but all in one physical unit.
I have a custom 4 channel UGLY battery box with two stereo minijack inputs and one mini-xlr output. I bought it years ago from TS user Printguy.. but it was nonfunctional on arrival and I never got it working. He had Chris build it for him for use into an R44. The mini-xlr output has a break-out cable to four RA 1/4" TS plugs.
I currently use two CA-UGLY preamps at the same time. Having two physical units is less of a hassle than dealing with all the wiring. One unit with 2 inputs and 2 outputs won't streamline your wiring unless you bundle the wires together to manage them. I sometimes place both preamps into a low-cut sock which temporarily "glues them together".
Hope that helps.