You should be alarmed. These exchanges always come up with devious ways to defraud members of the bitcoin community. I suggest you bombard them with reminders to return the bitcoins to you. Send them countless messages on their internal support system, their facebook and twitter pages, until they accept, acknowledge and recognize that perpetrating fraud is wrong and unconscionable.
This transaction system error you encountered is deliberately designed to confuse their clients. It is not for convenience. If you do not ask them to rectify the problem, I doubt they will voluntarily return the bitcoins to you. You have to consciously and proactively demand that they return your coins. Try not asking for it and they won't give it back. Fraudsters.
Someone from support contacted me two days ago and assured they will send it back to me within the day but guess what? still no bitcoins in my wallet. It's an expensive lesson for me, but its better that I have learned this sooner.
