Dual-camera plate for handheld?

I'm looking for a plate which would let you handheld two cameras and their mounted lenses (in my case they'll be e-mount so no worries about size).  Does anyone know of such a thing or what it might be called?

My searches result in a tripod plate for mounting two cameras side-by-side.  What I'd like is one that mounts them next to each other (the other camera is upside-down).