Are you sure you're not using the Matrox G200 for AH?
A G200 can do 1024x768 with only 8Mb of memory.
The Voodoo2 uses its memory diferently though. It is using 4Mb for textures and 4Mb for buffering and prepping (I think) the next frame. The extra 4Mb on the 12Mb cards is very rarely used.
I do not remember what effect the extra 4Mb would have. I guess that it might allow 1024x768, but I don't recall it doing that.
Its been too long since I read up on Voodoo2s. I have long since moved on to newer, faster cards myself. I do have a K6-III 450 running 2 12mb Voodo2s in SLI mode in my living room though.
Sisu
-Karnak