Why does PSE always ask me if I want to "Replace" my file when saving?

When working on a project, I like to hit the Save button every so often to save my work just in case my computer crashes or something. 

But every time I do this in PSE it asks me if I want to Replace my original file. Why? In every other app I use when I hit CMD-S it just updates the file with any changes since the last save. 

Is there a way to make PSE do that too? It's kind of annoying to have the Replace question pop up all the time. 

Thanks.