though if you think that the twitter contests main goal is to attract engagement (farm) then the bots aren't such a big deal, unless they start undermine credibility on the company too much
Partially they can check Twitter farm accounts and verify their quality by audit scores. These sites are not perfect but a company can use it as part of their toolkit to reject low quality accounts and increase effects from their marketing campaigns.
https://twitteraudit.com/https://www.followeraudit.com/The problem is the Casino doesn't require any specific number of followers for all participants. This kind of audit is useless on Duelbits giveaways since the only requirements for their giveaway are just the simple like and retweet task followed by the specific task for the event. A Twitter audit is only applicable to bounty campaigns in which the manager chooses the participants for qualification before receiving their rewards.
Also, this bot issue is probably not on Duelbits priority list since no one is pointing out this issue directly to the team.