When data is saved to the IBM ProtecTIER (TS7650, T7620, TS7610), the data is not compacted. This can cause extra media to be used when duplicating the volumes to other types of tape.
To ensure that data is compacted on the output or duplicate media, users need to specify COMPACT(*YES) or COMPACT(*DEV) on the DUPMEDBRM command.
When planning on changing the command default, refer to this URL
Reference this link for more information on the COMPACT parameter