Yes, demesisx and demeaning_casually are two alts of the same person. There were some others as well, I think they've all been banned at this point. They did the standard Lemmy bad-faith-person behavior of being hostile and obviously dishonest with the admin when the admin went to talk with them about it, at that point without the intention of banning them I don't think. For as unsuccessful a behavior as that is, it's pretty popular, I've dealt with it multiple times. I think the admin was able to find some more detailed information about it than I was, they caught a bunch of different alts.

The timestamps come from the time that votes get federated, which is often in batches a little bit after they were posted on the origin server. They're not reliable to the second. If I remember right you'll see batches of votes even from legitimate users come in all at the same time or within seconds if they're all on the same instance, and also there tends to be a reliable 30-second cycle on which they all get sent out in those batches. If you look on a scale of minutes, and there tend to be bunched-up votes from apparently different accounts that all are taking the same types of actions, that's more of a reliable sign of fuckery.