Maybe there is no bots, but the most possible thing is multi accounts to claim any code posted by duelbits.
I do not think it is worth to create a bot that can claim the code automatically, unless the bot is used with multi accounts as well.
Pretty sure that some people that saw the code earlier might have posted it in duelbits chat hence alot of players was able to claim it pretty quickly. Its free money and literally seconds of work putting that code so there is no reason not to when you saw it on the chat. Yeah some people could be multi accounting as well but it takes time to switch in between accounts right