Dell XPS 8700 BACKUP-RESTORE MEDIA

I just made a new Complete Factory Restore of my XPS 8700. I used an external WD My Passport drive. I cleaned and reformatted the drive before I started and the creation seems to have been successful.   I wasn't sure how much space it would take so I had this 500GB Passport available. The restore took about 10 GB.

MY QUESTION IS : Can I store other folders/files on this drive and it won't mess up the restore function?

Regards

JH