Win 7 EaseUS Backup - doubles backup

Recently added a terabyte external hard drive to a Dell Win 7 system. The computer is using 249GB; when I do the back up it takes up 500GB of space. I am using the EaseUS Backup software to do the back up and it has worked well for years. It is running on another pc and it works fine there also.
The external drive is a seagate. The first time I ran the backup it was 249GB just like the computer used space would lead you to expect. The second and subsequent attempts use 500GB. Any thoughts on how to fix this?

 

First thought is make sure you do not have it set for sector by sector backup which includes a copy of free space. If the drive you are copying is a 500gb then it seems likely that you do have it set to sector by sector. If the drive is larger than 500gb it may be something else.

 

I have checked my software and I don't find an option for sector by sector. The hard drive I am trying to back up has a capacity of 451GB and I am using 264GB. The drive I am baking up to is a terabyte Seagate USB drive.

 

This is a tiny picture but you can see the box for sector by sector under disk 3 and the graph legend with the colored boxes for partition types. Verify that is unticked.

http://www.todo-backup.com/images/feature-screen/business/disk-partition-backup-1.gif

 

Thanks for the quick response. Sorry for my delay in getting back to you. The picture helped and I have checked and the sector by sector box is NOT checked. We just purchased licenses for the Ease-us product and am working from a fresh install of that - same problem persists, but only on the one pc, the other runs fine. As far as I can see all the options are the same on both pc's.