sbbsimsg.js can send duplicate messages to the same user if logged in multiple times

When one of the users in the sbbsimsg list is logged-onto the same BBS multiple times and another user elects to send a telegram to "all", the first users will receive the telegram multiple times (one for each time they're logged-on), but those telegrams won't actually go to the separate node/session for each logon. More likely, they'll just be displayed in series in to one node/session as duplicates.