Is attaching a database on the same server under a different database name possible?
You can first check to make sure it actually is a valid MDF file using DBCC CHECKPRIMARYFILE. It is an undocumented command but can be useful at times.

If that turns up nothing or shows that it is not a mdf file you can use the RESTORE HEADERONLY to see if it might be a backup file.

To your specific question, yes you can attach this as a different database name as long as the physical file is not in the same directory on the server as the original. So in your case I would just create a sub-directory in your data folder for this file and the future LDF file that would be created.