Please note SplashID Safe Desktop app versions 7 & 8 do not allow multiple user databases at the same time. If you are using SplashID Safe Cloud Sync, you can logout, via the File menu, then login as a different user.
The Mac user data was migrated to the new sandbox:
The Windows user data is still in the same location as before:
You can import the backup files from the second user into the main account and then separate records using the Categories feature as it was designed.