yes and no. www.yahoo.com and yahoo.com still isn't treated as a dupe even though both URLs point to the same page (it's only a consistent 4 character difference), and I don't know how the same URL was able to be re-submitted without it becoming a dupe:
http://news.ycombinator.com/item?id=183903
http://news.ycombinator.com/item?id=177270
I'll probably start submitting links twice from now on