File names being appended with .numbers

I have several numbers files on my desktop e.g. "john". I find that this file name will change to john.numbers. This change often happens in front of my after closing the file and being synced to iCloud. I have found that it will often do this when I have previously opened it on my iPhone and may depend on whether I have edited or not. The settings on my Mac are for files not to include the file extension. Just a bit annoying. Any ideas please?