Rename the two files then thats it. 
No, that will not work, since internally, the .part.met file stores the .met file it belongs to. Simply renaming the files will not change that, and you will end with several .met files pointing to the wrong .part file, which will posibly lead you to lost parts of the download. You should use a program like donkeydoctor to change the .met file to point to the right .part file.
Regards.