Safari sharing cache/session between tabs

The files were locally cached and shared between multiple tabs when navigating a webpage after successful authentication.

1. Open a website on the first tab and authenticate. This will download some resources after successful authentication.
2. Open the same website on the second tab. It will log in automatically and load downloaded resources from the first tab.
3. Logout session in the first tab. This will automatically log out of the session in the second tab too.
4. Login again in the first tab. This time it tries to load already cached files instead of redirecting to authentication.

This step works fine in all other browsers in Mac, windows. It's only safari behaving differently.

Note: Making the js file public fixes this issue. But, why is safari behaving differently?