backup a backup

My current plan is to use Acronis TI to do my backups. I want to use 2 external drives for this. Drive 1 to make the backups; Drive 2 to back up drive 1. Then I will store drive 2 in a separate physical location.

In making a backup of the backup, should I simply do a file copy from drive 1 to drive 2, or should I do an Acronis TI to make a backup of drive 1 to drive 2?

Which is best?

Cliff