Is photography allowed at Lascaux II?
No. I was there September 2014.
We just visited a few days ago. It was wonderfully cool in the caves during this heat wave! No photography allowed, but there is a museum gift shop with many books, postcards, etc. of the famous paintings. We enjoyed the English-speaking tour guide.
They run hundred through the cave every day zip zip -- there is no lingering and in addition to copyright issues, I suspect the aggravation of people taking time and wandering to take pictures would cause it to be banned.