Copy db or a Restore should work. The restore would have to include renaming the physical files. It's easier to use TSQL, but if you want to use the GUI, click restore on the Databases folder. Type in a new name. Assuming a backup file, click on the From Device radio button and locate the backup file from the old database. Make sure the check box is selected next to the file once it's added to the Devices list. That should do it.

Of course, that assumes you backed up the other database.