Yes, if one card takes two power connections then two cards will need four power connections.
A 6+2 pin connection is a standard 6pin, but with an extra 2pins that could be used if you needed an 8pin. It's like older PSU's with a 24pin plug, which is actually a 20pin with a loose 4pin that can be used along side it.
See here for the difference:http://techreport.com/r.x/psus-0907/pcie-connectors.jpg
Left: 6pin Right: 6+2pin.