Now that I've gotten your attention, I seriously do think I lazily constructed a dual extruder mount for the i3v. I haven't tested it myself because I don't own two E3Dv6 Bowdens (I'd like to, though). Here's an STL I made from taking a recently uploaded i3v X-Carriage I found on Thingiverse and an i3 dual-extruder mount intended to be bolted on. I just merged the two together and BAM, an X-Carriage/Dual-Extruder mount, all in one!

If anyone has even a single E3Dv6, could you print this out and give it a test? If there are any errors, I can upload a SCAD file for modifying some stuff.
i3vdualex.stl