In Android, you can specify the texts in the default locale in res/values/strings.xml. Additional translations can be added for new languages in res/value
There is none which I am aware, I am favouriting the question. :) However as a best practice, I first complete the default strings.xml and translate it in the very end. I also add a small marker comment to specify end of translation and any new strings are added below that. This helps me keep track of ones which are not translated.
-- UPDATE --
With latest ADT tool for eclipse you can install Lint which takes care of all the issues regarding duplicates and a lot more with its exhaustive set of warnings.