They stopped making posts with the SteemCleaners brand after the rebranding. The last posts on SteemCleaner were in march.
It looks like they had a few days when they duplicated posts. Your are right. That was a big No No ... back in March.
There is a need for people to watch the watchers; So, I gave you an upvote. You were right about the short period of overlap.
RE: "Hello, World!" - We have a problem.