DigixDAO and TheDAO are two very different crypto assets. TheDAO is the largest crowdfunded project in history while DigixDAO is not. Both use the DAO idea.
Being paid for an idea like this is a bit hard, it's like asking to be paid for coining the term HTTP when it became popular years later. On top of this TheDAO is not controlled by a central authority so legal action right now is in a large grey area.
Thanks. I updated the post.