However, if you are selling the same hour of effort to two or more people then you are lying to, stealing from and defrauding them. That is totally black and white.
People are entitled to respond to the unfair state of the world in many ways, but it doesn’t justify theft.
As an aside, I am amazed at how sites like HN can virtue signal with the best of them, then conduct mental gymnastics to claim that double billing isn’t fraudulent. Cmon guys surely anyone can see this isn’t right?