Filling up LTO5 Tape for incremental

Good Day!!

Just a quick question if any have any thoughts/suggestions on the scenario below:

We have some incremental backup that needs to be send offsite - MWF.  I created an SLP that will do duplication to LTO5 tape. I had the storage unit setup to use one(1) drive of the tape library to make sure that it fills up the whole tape before writing to another but every time I check the jobs, it does not fills up the tape. Like today,the total size of the incremental backup is 92GB which should fit into one(1) LTO5 tape but it uses two tapes.

We use a T950 tape library that has ten(10) drives.

Any settings that I miss to configure?