Arun Sirpal discusses ways to restore a database within Azure SQL Database:
You won’t have the ability to use the same name of the restoring database and the database that you want to replace; if you try you get the screen shot below: To get around this I think you would need to drop the old one once the new one has restored then do a rename.
This is a big difference compared to the on-prem version, so be sure to practice this before you find yourself in a crisis.