Ghost callers in meetme conference rooms

We’ve noticed an issue recently where all of our conference rooms are getting populated with ghost callers (by this I mean you join an empty conference room and it advises there are already callers in the conference room even though the connections have been closed), my colleague noted that the following JIRA case seems to identify the issue and has an appropriate patch, we applied this to the server that the conferences are running on but the issue persists:

First of all, do we need to apply this patch to all of our servers? Or does it only need applying to the server hosting the meetme conferences? Are there any other potential causes/solutions that anyone here is aware of?

Any help would be appreciated.

System info:

CentOS 6.2
FreePBX Version
Asterisk Version
Incredible PBX 3 Version 3.0.6