Pinching a writing idea

Authors can become dispirited upon discovering another author has already used their plot device, a plot device they thought was so cunning and original. The situation becomes even worse when they discover the book they plan to write has a precursor. Someone else pinched your idea, except for the uncomfortable fact that they wrote it first, and had the idea before you did. It has just happened to me concerning an historical fiction novel. But the thing is two people can write about a similar subject in a completely different way with totally divergent themes. The truth is, I don't want to read the other book. I don't want to be sullied by the other person's approach. I will alter my perspective a little and hey-up off I go. Good luck to them, and good luck to me.