Lol, disgusting images right now. With the wine, I'd always assumed it was a spell like
I've a question. Wouldn't duplicating be much easier and seem more genuine with spells than Muggle forging? Harry could make more of that wine when he was at Hagrid's with Slughorn for Aragog's funeral. He didn't know the ingredients, but he was able to make more. And I'm guessing the extra wine didn't vanish inside Hagrid's and Slughorn's stomachs.
You could probably duplicate it, yes. Without magical intervention, I guess everything would be copied down to the codes and that picture of the Queen you get if you hold one up to the light. I wonder if wizards have charmed Muggle banknotes so that they can't be replicated by magic. If they were able to replicate them, I can see a lot of potential for crime and such.
Couldn't you do the same with other things, including money? Forget wizarding gold for a moment; what if you duplicated a Muggle note? They have these code thingies hidden in them, but with a spell, couldn't you use a duplicated one and get it by currency experts?