Duplicate files saved when backing up on the hard drive

When I backup my computer files on my WD hard drive I get multiple files saved.

As an example I see the original file on the drive called: Vitamin D Billboard_Invoice #467.indd and then below that I see another file named: Vitamin D Billboard_Invoice #467@b0a448064f4f4e07a138eb5a25165ec3.indd.

I am on WIndows 7.

Any suggestions why it does that?


What software are you using for the backup?

Make sure to check on the settings how many copies are you backing up. Change it to one or as many copies as you desire.