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.
Anyway with the fact that there are more than 100k followers, 2k code is just 2% so it is reasonable if the code is fully claimed really quick.
One more thing, the code comes without any other requirements, so it makes the code fully claimed even quicker.
I like that they are no requirements, in that way everybody stands a chance also the small gamblers. When there is free money, there will always be abuse with bots, multiple accounts... It is the same for the rain feature in chats also or with free faucets; everything will get abused.
I think like this as well, it is likely there are a few players out there using multiple accounts to claim those codes, but if they keep doing this eventually they are going to get caught, now it is obvious Duelbits is choosing to deliberately not introduce any requirements despite those cheaters abusing their offers as a way to give everyone a chance to claim them.
So anyone interested needs to be put a lot of attention so they can claim those promo codes before they run out.