When asking for help, please make it easy for people to help you. If you're posting code, click on the hashtag icon and choose "code", so you can post your code in a way that's much easier for us to read, including indents. That way people aren't forced to load your alias into remotes before they can even read it.
Also, if you are having a problem with a specific version of server software, it helps to give the name of a large network that's running that version, so we don't need to hunt through our server list in search of such a network.
When looking at something like this, the first thing I would ask is whether you are certain that everyone's address is in the IAL. Everyone who enters the channel after you should have their address in your IAL, but those already in the channel aren't in the IAL unless something happens to put them there, such as them making a chat message into channel, changing their nick, someone giving them voice, or doing a /whois on them, etc. If you do "/who #channelname" while you're in that channel, it should add everyone to your IAL.
Can you confirm that whois shows both people having the same identd? If one of them has identd enabled but the other one doesn't, it's possible that one nick has foo@hostname and the other one's address has ~foo@hostname.
Also, just observing that having the same username doesn't make someone a clone. Some clients default to having the client name as the identd string. Right now $ial(*!~quassel@*,0) shows me there are 81 matching nicks, and they're not clones - they just all use the same client