Renaming vm folder and files

After performing a rename of a guest within VCenter, the server has been storage vmotioned to rename the folder and associated files.  However, the nvram file has not been renamed, instead a new nvram file has been created which has the new server name, so there are now 2 nvram files in the vm's folder.

Does anyone have an idea of why this would be?

I would have expected all files to be renamed and not created as new.