For example on a computer you can use algorithms like lrzip, which search for very long distance redundancies (i.e. not in small data windows like traditional algorithms). This usually achieves a decent compression even on normally incompressible files, e.g. on collections of movies or on collections of PDF files, because it may find repetitions at least e.g. in the headers of the files or of the file sections. If there are similar files, then there are chances that lrzip will find repetitions between files, even if a traditional compression would not find repetitions inside a single file. If de-duplication is possible, then that would also be much more efficient than enabling the compression option of the tape drive.