Really? I thought it said in the rules no more than 6 of any card (including resources). Man my old gaming group screwed that up.
Kevin and I houseruled 4 copies max/card when we didn't find a card nr limit online or in the rulebook. For now I think we'll stick with that. :)
For those of you who care what the official rules were/are. It is and always was maximum of 6 of any card with the same name, except basic resources which don't have a set limit.