'm guessing your tests were run locally because the counter in the local
datastore does indeed have datastore scope. The scope of the counter in the
prod datastore, however, is parent key + kind. This is described here:
http://code.google.com/appengine/docs/java/datastore/creatinggettinga...
If it's important to you that the scope of the generated ids match between
dev and and prod please file an issue.