I have seen a case or two about managers enrolling their alt accounts in campaigns but they were mostly shitty ones like bounties and the managers were less reputable. These cases were discovered way after the campaigns ended.
For a reputable manager, it would be a very silly thing to do because if one is already earning from managing the campaign, why enroll alts? If the appetite for some sats is too much then why not use those alts to join other campaigns?
It's hard to tell or even suspect if there's any reputable manager who currently does such a thing.