A new tool that I’ve discovered: “Simian can be used on any human readable files such as ini files, deployment descriptors, you name it.”
http://www.redhillconsulting.com.au/products/simian/
Simian catches these and other instances of duplication [as described on the original page] and can be configured to either flag them as warnings or even "break the build", ensuring that copy and pasting never again causes you or your project problems.