You need to identify the backup set (or sets ) on the tape in Slot 44 and create duplicate jobs against each set that is on the tape in question (using append settings for all but the first duplicate if there are multiple sets and therefore multiple duplicate jobs)
However to ensure that tape in slot 45 is used you would have to partition the library so that slot 45 has a partition that you can send the job (or jobs) to - if you do not partition the library Backup Exec will use a combination the overall media handling settings, the media set specified for the duplicate, the status of every online tape in the library (including the last used dates of the tapes) and will make its own choice of which tape to use (which may not be slot 45)
