No, that's complete nonsense. Changing the savetype does not suddenly change the filetype of the save. Not to mention a file can't work with two extensions on it.
And just as a further note .bak is usually a fictional extension given to some programs that alter an original file but wish to keep a backup of the original so they just slap .bak on the end of a copy of the original so that if you ever want to use the original again all you have to do is delete the altered file and remove the .bak extension.
And just as a further note .bak is usually a fictional extension given to some programs that alter an original file but wish to keep a backup of the original so they just slap .bak on the end of a copy of the original so that if you ever want to use the original again all you have to do is delete the altered file and remove the .bak extension.