I got an email the other day from someone looking for a place to put some scores; I'm directing him to the site for now, but I thought I'd check on one of the files he sent me.
It looks to be a transcription for two Violas of http://imslp.org/wiki/6_Duos,_B.538-543 ... ,_Ignaz%29
. The publisher is International Music Company, transcribed and edited by Carl Paasch, plate No. 2542.
As near as I can tell, the only difference is that the viola version is down a fifth; exactly what you'd expect. I don't think it's eligible for copyright in the United States, but I thought I'd check here first.
I can upload the files if you'd like to check them out.