What is the use case for using the --extra-lsndir option of mariabackup?

I am modifying a script I found to create rotating weekly incremental backups using mariabackup. It passes this option to the backup command.

According to the docs the –extra-lsndir option creates extra copies of these checkpoint and info files.

When using the –backup command option, Mariabackup produces a number of backup files in the target directory. Using this option, you can have Mariabackup produce additional copies of the xtrabackup_checkpoints and xtrabackup_info# files in the given directory.

When would this be useful?