Save file keep overriding other save file

Hi everyone i would like to start that i share an account on the same device with my sister so we respectively have separate save files. Yesterday after my sister finished playing, i went to check on my sims only to find out that her save file overrode mine which is weird because she already turned her autosave file off. Thankfully i was able to retrieve my save file from going to the save file folder. This already happened twice to me, does anyone have this problem too?