angelina886 Please clear the App's cache:
https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/
and repair the game (EA App > Sims 3 > Manage > Repair). Then test again. If you still see duplicate worlds, move or rename the Sims 3 folder in Documents > Electronic Arts and look again. This will remove, but not delete, any saves or other user data you have, but that can be restored later.
If this doesn't help either, close the EA App and make sure it and the EABackgroundService are NOT running in the Task Manager; the latter would be under background processes. Open [install location]\The Sims 3, here by default:
C:\Program Files\EA Games\The Sims 3
and delete the Data folder, then repair the game again.