I always found it odd when accessing network shares between users with the same name and password that it never prompted me for one.
It was a great workaround back before active directory. If you didn't have access to a share, just figure out the owner's username (pre-populated on their lock screen), and create a new local user on your machine with the same username, connect to the share as that user, done.
If the facts don't fit the theory, change the facts. -- Albert Einstein