Second revival of this thread!

So is the main body of the duopar (the part that bolts to the dropout and supports the "first" parallelogram) supposed to be able to freely rotate about the dropout the way that most derailleurs do? Or is it supposed to remain fixed in place, while the "second" parallelogram takes care of positioning the jockey wheels closer to or farther away from the cogs.

I just installed a Duopar on a frame with a Shimano-style dropout hanger, and with the tabbed and keyed washer at the dropout stop, the main parallelogram is at about a 45 degree angle.