The one-hit wonder is a funny thing. If I asked you to name three off the top of your head, I bet I could argue that at least two of them weren't, in fact, one-hit wonders. Just have a look at the ludicrously convoluted Questions of Definition section on Wikipedia's One-Hit Wonder page and you'll see where I'm coming from here.
In short, Carl Douglas had two hits besides Kung Fu Fighting, the Buggles had a second top-20 hit, Edison Lighthouse are no more one-hit wonders than The Timelords and if you honestly think that the Boomtown Rats, Dexys Midnight Runners or a-ha count, you need to look up 'parochialism' in a dictionary. I'm tempted to argue, though, that in 4 Non Blondes, we may have a winner*.