Q. How do I cite two book chapters that were written by the same person, that appear in the same book?
I have your answer about how to cite those two chapters. Before that, I just want to be sure that you got the Place of Publication and the Publisher, 100% right though. When you cite these, be sure to also include the abbreviation for the state, as in this example:
Boston, MA: Cengage Learning.
With regard to the two chapters, I'd recommend differentiating the two citations with the lowercase letters "a" and "b", doing so both in your References page and in the in-text citations. See this page on the APA Style Blog, which is about using this method to differentiate between two pieces that were written by the same author(s) in the same year: http://blog.apastyle.org/apastyle/2011/10/reference-twins.html.
BTW, to find this on APA's site, I searched the terms multiple chapters same author.