Well, you can't get two wickets off one ball, so I guess they were really going for one or the other. Good bit of thinking really.
There's a link on that same page to the underarm bowling incident in Melbourne in - what? 1981? - and it's actually the first time I've ever seen it. Richie Benaud's editorial ("the most disgraceful thing I have ever seen on a cricket field") seems to me to be bang on the money.
YouTube - Most disgraceful moment in the history of cricket