Hi There
I think your suppliers are getting confused between the Hercules Prophetview 920 (DVI and Non DVI) and the hercules Prophetview 920 Pro (DVI and Non DVI)
The former is discontinued the latter are in high demand and are thus very hard to get hold of.
As for other monitors being the same the panel is used in the hercules is used in a couple of different displays I dont know the model numbers offhand but I would imagine that the Hitatchi uses the same panel but you would have to confirm this with them.
I know there is supposed to be a new supply of the non dvi's soon and the dvi's in a month or two
Hope that helps