Using XML files and playerprefs together

I am developing a stand-alone game where potentially 20 users will have their own save file located on the same computer. At the moment, I am saving their data to individual XML files. I was wondering if it was a good idea to first load user data from the XML file and then, use that to populate the playerprefs so I can pass data freely among all levels. Then at the end, I output all playerprefs to the user save file.

Then when another user logs in, the playerprefs are reset with new data.

Would that be smart or good practice? I just didn't want to make too many static variables for my user.