I can only find 4 other accounts consistently getting upvotes by 80 odd accounts, a couple of them are the same 15sp accounts that were identified 9 days ago like you said.

I have removed the rewards from these comments
https://steemit.com/@brandonolan/comments

Are you able to remove your upvote from this comment please?
https://steemit.com/hive-172186/@brandonolan/qlaqo4

Good spotting by you, i am still looking for others and think since we busted their first farming plan they may think upvoting comments may be less visible ..haha