That will be the crappy casting, mine is like that and never caused a problem.
Mine was standard until i put the 48 tooth one in this week, and it had a friction plate in first. No dished plate anywhere but remember this is a ducati you have bought and the spec bears little resemlence to what you actually get. Sometimes you win and some times you lose.

You should have about 4mm of drum exposed once all the plates are in place.
As keith said, the pressure plate gets cast, rather thinly, then machined hence the holes. It'll be fine :)

Thanks for all your input!