Comment 1 for bug 802868

The software center spec doesn't provide any reason for multiple recommendations against the same review. In fact, we built the client to keep track of usefulness submitted and hide the yes/no buttons if the user has already submitted usefulness for that review.
But it was implemented in Natty with only a local cache which is updated on submit of usefulness, which means it is not perfect. For Oneiric, I've already re-written it to retrieve the usefulness votes from the server for the currently logged in user so it should be more reliable.

In any event, the server should probably stop multiples from being possible.