I am doubting that very much. You're referring to the thing I know Vodacom has running, the one is called Twin Sim, where you can have two numbers on the same sim. Obviously the primary sim gets priority, you can't have both active at once. The other thing Vodacom has is a Data-sharing sim, I'm not sure what they call it, but it does exist, and there quite a few people who use it.
Looking at this article:
http://mybroadband.co.za/news/cellular/28007-8ta-dual-sim-for-data-considered.html
I'm doubting that it has been implemented yet. As we all know in the field of technology and those of us who have experience with Online Banking - when a company says they're considering something, it means "Hey, that's a good idea, we'll look at it when we're bored." When a company says "The feature is being implemented" - they simply mean, "Ok we're bored, but too lazy to implement the system right away." So perhaps give it till the middle of end of 2012 and I'm sure they may have implemented the feature by then given considerable demand from the public.
Also, this is just my speculation based on that article link, and obviously, South African service delivery, the best would be to call 8ta, actually there's a rep on the Mybroadband Forum, he replied to me about something in an OKAY timeframe, here's the link to his profile, drop him a reply and let us know what he says if that's cool with you:
http://mybroadband.co.za/vb/member.php/148423-8ta