[_ap]

I can't say for sure, but the ending quote from the article

  “I have to share the credit,” Bradley joked. “I may have
  invented it, but I think Bill made it famous.”

seems to support the theory that he reinvented it independently. I'd be interested to know who at MIT picked the key combination Ctrl-Meta-Ctrl-Meta-Rubout for the Lisp Machines.

[ScottBurson]

It was almost certainly Richard Greenblatt, who built the CONS prototype (there was only one built) and then the first CADRs.