Nope! I have never seen one like it! At first I thought it was a halter / bridle combo, but its not. I wonder if it was custom made - looks like they took the throat latch and made it the cavason hanger - then added a secondary stabilizing buckle in the same place you would expect to see one on a lunging cavason.
I got him and it from Germany (only 1.5 hours from my place) they said it was a special one but I didn't think to ask anything more...They're due out for a visit so I guess I'll ask then if nobody can figure it out here