Looks like a bot. Why will a spammer like to leave so much of proof behind ?
A possible solution to this case it blocking a member from making posts with repetitive content. I do not know how much of work it will take to integrate this on this forum but I have seen such features on other platforms.
I don't think that they expected to get caught. They are all jr member, member, full member and even a hero account.
It is hard to create original content when they are farming that many accounts.