Do the accounts themselves look off somehow?
Behaviour like this is sometimes called
One person running several accounts so that a single voice appears to be many independent ones.
Organised activity dressed as a spontaneous grassroots movement, run by a concealed interest.
Coordinated inauthentic behaviour
A platform's own category for coordinated activity that relies on fake accounts to mislead people about who is really behind it.
What would tell them apart
One person running several accounts so a single voice looks like several independent ones agreeing with each other is one shape. A funded or organised interest concealing who's actually behind an apparently spontaneous show of support is a different pattern again, and can be done entirely with real people using their own accounts — the concealment is about origin, not identity. A platform's own enforcement category for this turns specifically on whether the accounts themselves are fake, which is a narrower question than either of the other two.
Why it might be none of these
Keeping separate accounts for work and personal life, or a pseudonym kept apart from a real name, is normal and often necessary for safety. What would point toward something else is those separate identities being used to simulate independent people agreeing with each other, not the existence of more than one account.
None of this covers stalking, doxxing, swatting or harassment campaigns. If any of that is closer to what you're facing, go straight to Red lines instead — the advice on this page was not written for it.