Prevent File Copy Where Source And Target Are The Same File?

In my program I allow the user to copy a file from one folder to another. If the file already exists in the target folder I want it to be overwritten.

All that works just fine - I'm not asking how to copy files.

But here's an example

Source file is:-

\SomeMachinesomeFolderfile.xyz

Target is:-

P:file.xyz

This might at first look like two separate files but in this case P: is mapped to \SomeMachinesomeFolder so the source and the target are actually the same file and the file copy will obviously fail.

Of course I want it to fail but my problem is that the windows generic error message seen by the user is not very helpful. It says something simple like "... can't be copied because it's busy". If the user isn't very bright he doesn't realize he's selected the same file both as source and target and he doesn't understand why it's busy.

What I want to do is detect in advance that the source and the target are the same file and display a more meaningful message to the user and not even bother trying to copy.

So, is there a way to detect that

\SomeMachinesomeFolderfile.xyz

and

P:file.xyz

are actually the same file?