Posting the same stuff on multiple platforms is a no-go in my opinion. It’s about fair play. I mean if some viewers use DTube only or DLive only for example, then okay they could miss some content. That would be a legit argument to do this.
But I guess we all know why these specific people are doing it. It’s about maximizing profit and the hope for an additional huge platform upvote, nothing else. And that is very, very poor!