This is a real problem. I see this too. I haven't figured it out. For some reason Google appears to be associating CWB files to WAV. I checked the browser (FF) and it's not doing it nor is Windows. If I put a CWB on the drive for my buddy, it's fine. When I bring in one of his, ".wav" has been appended to the file name so I see it as "song.cwb.wav".
I asked the Google forum about it too but got no replies. It only started happening recently (about 2 months ago.)
As far as a quick fix, just rename the file to .CWB. You can also tell Cakewalk to open *.* and it will see the .wav, you can open it like any other .cwb file and re-save.
The value of bundles is a totally different subject.