I want to ask that sometimes we report these types of accounts but moderator didn't took any action so in this case these accounts should deserve negative?
Even if the moderator does not take immediate action against such users, you can monitor their behavior in the future, and if they continue with the same behavior, report their new posts to the moderator once more. It is also a good idea to leave a neutral tag on their accounts with a reference to a post containing evidence, just like this one.
In Utopia weekly review bounty I found many accounts which created in same day and all accounts have the same posting style( Posted UTOPIA #POA in 4 other bounties thread to increase activity). The gang of these cheaters created more than 20 accounts to grab all reward. These accounts are abusing forum rules So there is anyway to report other than bounty manager reject them?
If you have some solid evidence that these are alt accounts, it is definitely a good reason to slap on a negative tag because that is an abuse of the bounty campaign rules.