If you are sure about a person using multiple accounts on a bounty and trying to cheat the bounty manager then you should first collect proper proofs of that user who is using multi alt accounts on a bounty campaign, and if you have collected the proof then you should either open a thread by showing it to the forum or report it to the bounty manager.

It's not really a worthy thinking to involve our beloved moderators in such things because it mostly falls in the domain of bounty manager who is running the campaign. The moderators have more work to do then searching for the ones who are cheating the bounty campaigns with multiple accounts. Although, they try their best efforts but still a little help from a good user is a appreciatable thing.

You should also try to search for anyone who is using alt-accounts on bounty campaigns and report it to the bounty managers when you have proper proof, that way the members of the forum will also appreciate your hard-work. It's really not worth it to get emotional on such things because scammers and cheaters are everywhere, and the ones who detect them are truly respect-deserving ones.

The bounty managers are doing really hard work in running those bounty campaign and sometimes they also have limitations as human beings. It's the work of a good member to report the scammers and cheaters to the bounty managers so that they could penalize those negative actors by removing them from the bounty campaigns. And reporting them to the moderators and administrative staff, so those cheaters can be penalized with a ban.