For now at least, but still the idea of alt accounts basically trying to change polls so that something happens is not much of a threat, since most polls here are mainly made by regular users which are mainly polls with weird, or regular crap and stuff. While the rest go to moderators, which moderator polls would be the target, but since most polls here aren't made by moderators daily, it isn't a threat as of now.
Ok so if something like this were to happen where alt accounts by a single user come in to try and change the poll votes for a change, I don't know what's gonna really happen. My best guess I could say is that we'll try to stop that user from doing that again, and once so, he/she would either stop, or either get blocked. That's my best guess as of now. I mainly document onto vandals with alt accounts that try to destroy the backrooms wiki, rather than document users with alt accounts to change posts that try to destroy the backrooms wiki.
Never seen a user who makes alt accounts to change poll votes, but one day we may see one on the rise in the near future.