Use a Virtual Copy. In the Library module, right-click the photo and choose Create Virtual Copy. This gives you a second Lightroom version that you can edit independently from the original.

Because Lightroom uses non-destructive editing, both versions still point to the same source file on disk; Lightroom only stores different edit settings. If you need separate finished files, export each version when you’re done.

If you just want to save different stages within the same editing workflow, you can also use Snapshots in the Develop module. Snapshots are useful for bookmarking points in your edit history, while Virtual Copies are better when you want distinct versions of the same image.