This comes from the BBC (it was posted as part of an article describing how the plots for the series Broadchurch were kept secret):

"As the whole series [of The Apprentice] was filmed months before transmission, the two finalists would BOTH film an initial ending in which they were told that they'd been hired. In the months between filming and it going out on TV, the finalists would then both work for Alan Sugar. Only when the final was about to be transmitted would he tell them who had the job. It meant that for a long period of time, Lord Sugar was usually the only one to be in on the secret. "

Comes from here: http://www.bbc.co.uk/newsbeat/30680039

The article makes it pretty clear that it's referring to Series 1-6, and I think even Sugar himself openly acknowledged that was how things worked back in those days.

That said, they apparently do still film two endings, to help keep the outcome secret from the press. It's just that now Sugar does (provisionally) make the decision who he's gonna invest in there and then.