I'm an English major, since you were asking, and this topic has come up before in my grad classes. It's unethical. That's what most of my professors have said, however, I have to agree with another poster about papers from a larger project: my thesis advisor initially presented a proposal for a book at a conference, nothing flushed out, just ideas and some proof. At the same conference a year later, he presented on the same project, except this time he had a substantial amount of work done and the paper was essentially not the same as his initial presentation. His overarching aim was the same, but he presented on a scope of that larger project. I don't see the harm in this, but the same exact paper serves no purpose when you return to our discipline's crux that we contribute something to a conversation when we write, present, and publish.