Simultaneous discoveries are so common it would be strange if he hadn't.
But simultaneous discoveries that predate humans sound pretty fantastic to me. They claim these handprints were made by Neanderthals.
If you take you hand, dip it in a riverbank so it's covered with mud then press your hand against the wall that is what I would call an intuitive way of making a handprint. Laying your clean hand against a wall ans smearing mud around it so when you take your hand away there is an impression of your hand from where the mud didn't hit? Not so much. Throw in a cave so someone has to be standing behind you with a light so you can see what you're doing and it's even less intuitive.
Funny thing was the artist didn't even bring that point up at all. he waxed on about the wonder of humanity. Like I said in my OP, he was kind of goofy.