In Android, you can specify the texts in the default locale in
Interesting question. I've wrote simple script to find duplicate resources in android project at https://gist.github.com/1133059. It is ugly, I know, but I'll rewrite it in a few days and maybe create a project on github.
To run it from console:
$scala DuplicatesFinder.scala /path/to/android/project
I've made a project on github https://github.com/4e6/android-localization-helper, maybe someone find it helpful