I ran across a term that is the correct one for the multi-identity posters. Maybe everyone else already knows this, but I hadn't heard it before.

Quote:

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A sockpuppet is an online identity used for purposes of deception. The term, a reference to the manipulation of a simple hand puppet made from a sock, originally referred to a false identity assumed by a member of an Internet community who spoke to, or about, themselves while pretending to be another person.[1] The term now includes other misleading uses of online identities, such as those created to praise, defend or support a person or organization,[2] to manipulate public opinion,[3] or to circumvent a suspension or ban from a website. A significant difference between the use of a pseudonym[4] and the creation of a sockpuppet is that the sockpuppet poses as an independent third-party unaffiliated with the puppeteer. Many online communities attempt to block sockpuppets.

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https://en.wikipedia.org/wiki/Sockpuppet_(Internet)