This is probably a terminology mixup, but names are
trademarked, and not
copyrighted. There is a big difference. Copyright cannot be applied to such a short phrase... that is what the purpose of Trademarks are for. (See
US Copyright Office FAQ for details)
Of course, that is US copyright law that I'm talking about, but I'd assume it is similar in Japan...
I'm leaning towards "fake rumor" at the moment, unless someone can get me the original article... of course the terms are mixed up often, so maybe the original article screwed up on that part. I'd assume Nintendo of America would register their Trademark to protect their rights... so we should be able to search it.
Unfortunately, I'm not a lawyer and the
US Trademark search page is a bit more complex than I thought it would be. Someone who knows more about this stuff should see if this claim even holds true.
EDIT: Okay, I tried searching the US Trademark dictionary and...
http://tess2.uspto.gov/bin/gate.exe?f=brwsidx&state=spmc9n.1.1
Nothing found. I don't see any proof that Nintendo of America has even attempted to register the name yet. Of course, the US Trademark and Patent office may be processing the trademark application... but regardless, I don't see any evidence for "DuskGold" getting registered.