I've not taken the SCWCD yet (but plan to next year). However I might be able to help explain the difference between the "Core Servlets and JSP" and the "More Core Servlets and JSP"(both by Marty Hall, a super instructor!).
According to the site for "More Core Servlets & JSP" the book is a "companion book" for the "Core Servlets & JSP". From the reviews on the web pages it looks like "More Core Servlets..." addresses the newer technology. "Core Servlets..." uses JSP 1.1 and Servlets 2.2. "More Core Servlets..." uses Servlet 2.3 and JSP 1.2 standards.
Go to
http://www.moreservlets.com/ to see what Marty says about "More Core ..", and
http://www.coreservlets.com/ for "Core Servlets..."
Also the "More Core ..." explains describes Web application development, deployment, and security in detail.
I would recommend picking up a copy of the "More Core Servlets & JSP" if you are going for the certification. I'm personally using the Hanning book, in addition to experience.
Good luck!