Larry may have known the technique because of Vernon, but if he did, I never saw it. He did not use it in his regular work.
I also never saw Larry do a Second Deal, and I can't recall any tricks in which he used one (though I am sure there are a few). He DID use a Bottom Deal, though, so it would seem to make sense that if he did a great Second Deal, he would have put it to use.
I wish I could announce the publication of "Mr. Jennings Takes it Easy" on Tuesday, but alas that won't be the case. What's coming will effect and be of value to many more people than the pool of potential customers for that book.