Some files mirror and others simply copy

Using a WD 2T Elements drive on Windows 7 laptop.   When I drag images like jpeg and tiff they seem to mirror because when I delete them from the laptop after being copied to the WD they get deleted too.  The odd thing is when other files like .doc or .xls are copied over to the WD, they don’t get deleted from the WD when they are deleted from the laptop drive.

Any solutions or answers to this would be helpful.  Thank you.

You seem to be using a program that syncs the files from your PC to the Elements. Check if you have anything like that installed, also try connecting the elements to another PC to see if the same thing happens.