My Passport Ultra capacity very low

I use a My Passport Ultra 1 TB to backup my data. My pc is a Lenovo H500S with a Samsung EVO 1 TB SSD, and I use Windows 8.1 64 bit.

My internal 1 TB hard drive shows 672 Gb of free space, but my external WD 1 TB hard drive that I use for backup shows only 300 Gb of free space. On my external drive Other Backups is 116 GB, and Additional Files is 465 GB. I have the number of backup versions to keep for each file set at 5, but in Retrieve in my external drive it shows very few files with more than a couple versions saved. Why are Other Backups and Additional Files so big?

These are the folders on my external hard drive and their size in parentheses:
1)File History(263GB)>Jake567(263GB)>LENOVO-PC((263GB)>Configuration(263GB)>Catalog1.edb, Catalog2.edb,Config1.xml,Config2.xml

DATA>(263GB)>$OF63.0GB)>hundreds of numbered folders

C(200GB)>USERS(200GB)>Jake567((200GB)>ten of my folders

2)Temp(0GB)

3)WD SmartWa.swstor(0)>LENOVO-PC(0)>Volume.c5c1…(0)>FRST(0)

4)WDSmartware>swstor(425GB)>LENOVO-PC(425GB)>Volume.052e5a…(71.6GB)>four folders and four documents

Volume>c5c1e0…(353GB)>same folders and documents as in Volume.052e5a…plus a few more

.comwdc.metadata.xml(1KB)

There is a lot of duplicating of files and folders on my external hard drive. Can you tell from this list which folders I can safely delete? Why is my external hd duplicating so many things? Thanks for any replies.