Mysterious Appendages – .jpeg

One of our users called up stating that when they recieve an e-mail in exchage, the attachement arrives with the extension .jpeg attached to the exsisting extension.
example

Jazztoad.jpg.jpeg

We can open the file by deleting the .jpeg appendage and renaming the file.

The user is on a Windows 95/98 machine and the files are associated to Microsoft photo editor.

What gives?
Thanks