Catalog Backup using more than one tape

Hi there,

Our catalog backups were running fine, and now I find that nebackup is using two tapes for a catalgoue backup. 

We are running 7.6.0.1.

The first task writes 500 MB to one tape, than another task kicks off which writes 2 GB to another tape. We are using LTO4 media.  Prior to last week, catalog backups were utilizing one volume.

Can anyone offer any insight into this behaviour?

Thanks

Seth