thank you for the reply Stewart.
As you are assuming, we have more than one drive (actually two drives, i´m sorry I didnt told it on my first post) but each backup job is attached to one of the two drives, not to both of them (I cant really tell you why, I guess the person that configured it this way had good reason)
What you advise me to do it´s already done for each backup job, but we still have the problem.
I´m afraid of the disadvantage you mention: If a mount request is generated for the first backup job and no one is there to take action we wont have backups for this day, and this a bigger problem than having a backup on an "incorrect" tape :)
Anyway, I am very grateful for your help Stewart. I´ve seen other posts that maybe are related with this problem and checked the preallocation list for each backup job. I dont know why but not all of the tapes asigned to each pool appears on the prealloction list. I´m thinking on adding all the tapes of each pool to the preallocation list of each job. Could this solve the issue, or improove the behaviour? Could this addition generate another mount request?
thank you so much.