The Man Who Folded Himself question

I started reading this book, and I have a big question about time traveling, how it is described in the book.

Dan says, that he could strangle himself as a baby in the past, and he would not cease to exist.
However, when he makes a restaurant reservation in the past, it appears in his present as well.
So in one case, the change made in the past does not affect the future, in another - it does. Am I missing something or is author's reasoning not logical? In any case, what would happen if Dan strangled himself as a baby, according to the author?

Also please do not post too many spoilers, still hope to finish the book :)