Anand -
I can't say that I've had a font not "copy." This might be an issue of your third party not having the font installed on their system. You can use "truedoc" to embed the font in your file so that won't happen.
Ariel-
Create a file with text. On 1/3 of the text use Arial, the next 1/3 use Times Roman, and the final 1/3 Swiss (or substitute whatever you like). Now save the file. Next change the Swiss to Arial and make sure you have highlighted even the spaces so that no code is still present (essentially eliminating the use of that font in the file). Once again save and close the file. Make sure you have uninstalled Swiss in BFN. Now open the file and you should be prompted to install Swiss (even though the file no longer is using that font).
The file still retains the Swiss font info, even though it's no longer used in the file. I have had this happen when I take files to a service bureau, a sign vendor, etc. And it's not something isolated with Corel, when I worked with Professional Draw on the Amiga system, the same would happen. I know someone may conclude that some code is being deleted because it's a space, but I'm very careful when designing and don't believe that's the issue. I think code remains even after it has been deleted. Perhaps what we need is a magic decoder magnifying glass that passes over the page and highlights stray code to be eliminated?!