"Duel with bet" Question

No and next time send a message and even better, use the search button instead of opening a new thread because this has been already discussed both ingame and forums.

Ingame duel bets between players are being done as on any other server, at your "risk" and I'm talking about the risk that the opponent won't pay his bet. Note his name down, don't duel with him again and that should be it.
The only way of making sure someone is keeping his word is through a GM duel bet while the GM holds the runes and gives it to the winner, however GMs won't be around to host GM duel games all day long. You can always contact a GM and see if he has some time to spare for a gm duel bet game but make sure you don't spam the main channel asking if there is any admin online for your duel game and always use /whisper instead.