This is two Wade extruders joined together. The mounting holes from the second extruder have been moved, and they're just a few mm off being joined by the centre hole. This is so that the pair can be mounted across the x-axis rather than along it without hitting the standard Mendel X drive belt.
You will need to use the collared drive gear as few motors I found had shafts long enough.
This uses mendel.conf and mendel.inc from http://www.thingiverse.com/thing:2192
Print and fit 18mm PTFE or PEEK insulators with woodscrews. Print the main extruder body, one collared gear, one large gear and one idler bracket. Add NEMA17 motors, gears and shaft etc. much as per the parent object.
For a suitable X carriage, see http://www.thingiverse.com/thing:6805