Just looking at their usernames and the complete lack of originality from one to another, I have no doubt this is probably a single person or maybe a few. I'm not sure how many "farms" exist where there are actually multiple people working on bounties, but we all know there are individuals who have multiple accounts enrolled in the same bounties. This number of accounts would be a lot for one person to handle, though.
cryptodevil has already tagged several profiles for similar actions.
Wow, I haven't heard much from him lately nor have I seen any recent posts from him. Is he still busting ICO scams or what?
Anyway, good catch on this, OP. I clicked on a couple of their profiles and those weren't wearing any signature. Are they currently enrolled in a bounty? If so, you might want to bring this thread to the attention of the bounty manager.
Edit:
But I want to hope that managers themselves will be able to notice such a revival in their campaigns.
Their writing style is very similar and attracts attention.
It isn't likely that a bounty manager is going to catch cases like this on their own, though I imagine it depends on the manager. Some don't care and wouldn't bother to pay enough attention to posting style or similarities in usernames and registration dates. In fact I would say most don't give a shit at all and won't ban these bots/farms/alts unless someone brings it to their attention.