Twitter's most recent update to its terms of service state that it is a direct violation of terms of service to Tweet the same content across multiple accounts. To protect our users from incurring suspensions due to violations, we have restricted the ability of our users to post content in any form across multiple accounts.
We have, however, allowed users to utilize a Twitter account that they control in order to post content across multiple Twitter accounts. This is only allowed, however, if those Tweets are Retweets. dlvr.it has restricted this function, however, to only allow automatic Retweets to 5 Twitter handles. Twitter has indicated that Retweets are permitted of the same content as long as those Retweets are to accounts that the user controls from an account that the user controls.