Hi,
What you're looking at here is partitioning your autoloader. So you'll be logically breaking it up into groups of slots, and pushing jobs to that.
Under Devices in Backup Exec, navigate to your autoloader, and right-click it, before choosing Configure Partitions.
You can then create your slot partitions as need be.
From there, go into your job/policy (then job), and into it's properties. Under the first tab called Device and Media, you can then set your job to point to a specific slot.
I don't know if you have a duplicate job in place yet, but you'd create a duplicate job to run at a certain time, on a certain day (shortened version here!), and duplicate a certain job. Once again, you can go into your duplicate job and point it to specific media.
You didn't mention how your backups are structured, or how many slots you have in your autoloader. What I would do from my side though, is duplicate to separate tapes. That's just my preference, and I would have better control of tape locations, what's on them in terms of data etc, making management easier.
If you're strapped for cash, or don't have enough tapes, you could set your tape to Append to media, terminate if no appendable media is available. This will make sure your data isn't erased, and you'd still have data on the tape even if all your data wasn't duplicated.
Laters!