Well I don't see any problem with it because as fas as I know those bounty managers have the consent of their clients. Besides, a bounty manager has a lot of on going project that is why their signature and avatar will always vary depends on what they want to wear.
I agree because one bounty manager can hold multiple bounties and it has no rules at all so there's nothing funny in this
I thought it was natural and maybe this problem already be resolved right Gift Managers Wearing Signatures another
Their cleint should not avoid them to use different signature because it is included on their contract. Besides the only job of bounty manager is to handle and manage a certain project. It is not their job to help the project to advertise or endorse the project.