It has been about a year since I last used CloneZilla, but I believe when cloning with a larger disk it will give you the option to expand the partition to use all of the available drive space. Doing a quick Google search CloneZilla doesn't clone to a smaller disks. I did see some other programs that can be used to shrink the partitions on the disk before cloning. I don't see how disk to disk multiple times would work since the cloning usually wipes everything from the backup disk before cloning.

If you want multiple backups to the same disk you will need to use the disk to image option https://clonezilla.org/show-live-doc-content.php?topic=clonezilla-live/doc/01_Save_disk_image but as I mentioned before unless you also restore the image to another disk you won't know if the backup will restore correctly.