What problems could occur if a system allowed a file system to be mounted simultaneously at more than one location?

The correct answer is, if a file mounted at more than one location, it will give support to mistakes confuse the users.

Explanation:

Mounting: A process by which operating system makes directories on hard drive, floppy disk, CD-ROM or network share (types of storage devices), which are access via file system of computer and available for the users.

So, if a system is performing these type of tasks continuously at the same time, the user will get confused and a lot of mistakes will occur at that time.