Two sets of them from different countries:
1. From Vietnam:
- emikotadami (https://www.mycast.io/profiles/239687/username/emikotadami)
- tadakoyunemi (https://www.mycast.io/profiles/245717/username/tadakoyunemi)
- hanamisakurai (https://www.mycast.io/profiles/239584/username/hanamisakurai)
- hanakosakurasawa (https://www.mycast.io/profiles/239916/username/hanakosakurasawa)
- tadashiyukito (https://www.mycast.io/profiles/240771/username/tadashiyukito)
- lquyenhoang (https://www.mycast.io/profiles/249850/username/lquyenhoang) (idk, this one probably one of them. Kinda sus tbh)
I know these were the same person using multiple different accounts. The naming patterns in their usernames, their similar casting suggestions, and voting on each other's castings says it all. Also, they tend to go after fancastings of live action adaptation of anime and manga. There might be more but that's all for now.