My understanding of how this works is that that left one is real accounts making real comments, at least in the majority.

Then when the link gets reposted, either by a bot or naturally, potentially depending on the title, the bots scrape the old comments and post them.

It’s content farming. And Reddit is probably okay with this.

The right one is the “real” accounts. Notice how the left one is newer and all the accounts have names ending with four digits, except where they aren’t copies from the right.