If you have recently updated your Windows computer to Windows 10 Fall Creators Update (v1709) or installed any Windows Update, and are facing a problem where you see the login screen appearing twice, you can fix the problem by making use of these two solutions.
Login screen appears twice in Windows 10
1] If you were using some older Windows version and you have recently installed Windows 10 v1709 update, your system will automatically use the sign-in information to make the device ready for the new update. This is the main reason, why you see the login screen once more even after entering the login credentials.
You can disable this feature from Windows Settings panel. Go to Accounts > Sign-in options. On your right-hand side, you should find a Privacy category. By default, the Use my sign-in info to automatically finish settings up my device after an update or restart option is enabled.
You should toggle the button to the Off position disable this functionality. After that, you should not find the same problem appearing on your machine.
2] Although the solution mentioned above works in different cases, you can also use this trick to get it done. Open the User Accounts settings. To do so, press Win + R, type netplwiz and hit the Enter button. You will find an option called Users must enter a username and password to use this computer. By default, this option is enabled. You need to remove the mark from the checkbox.
Now, you need to enter the username and password and restart your computer. After restarting your PC, open the same dialog box and re-enable that same functionality.
In simple words, you have enabled auto login and disabled it again.
Hope these suggestions help you.
Related read: Windows logon screen appears twice when you resume computer from Sleep