http://2.bp.blogspot.com/-iRitb3pecOg/TdWVKvPATXI/AAAAAAAAC3I/_dP2gtYbgx0/s1600/patch.jpg
There it is!
Left = the one in question
Right = my Donna bag
You can tell from the photo that the left patch "pops" up. If I press my finger on it, it pops up & down like the cap on those juice bottles. The Donna patch is thicker and flat on the bag. I also tried pushing the bottom corners out from the inside of the left bag.
The eBayer said she purchased the Rocco from forwardforward and it may be possible that she switched up the dustbags between her Wang bags, but even then wouldn't the patch be the same?
If it's the real bag, I also think Wang himself might have changed it up between the years to save material or something? I'm not sure if my Donna is older or the Rocco though...