Okay, sorry for the long delay - Christmas has been a bit busy, and I wanted to get that dungeon done, so I was prioritizing what I was dealing with. ;P
Anyhow - yes, you can get two Akia's if you group up, and each one of you starts the quest. I could prevent that (by checking whether Akia has already been summoned for that group), but I actually chose against it when making the quest, so low-level players that are having real troubles with Cladt (you complete his quest at level 6-7, and it doesn't leave much room for error then) can group up, get twice the healing, and pass the quest. Kudos for noticing it, though (I thought people would notice it a lot sooner, but yeah X3).
And yup, I'm aware of the timer bug. The problem is simply that the timer is cancelled on your client, the server realizes that you're no longer doing CH the moment you leave the map.