Issue with multiple sd-based swaps being active after boot-up is solved.

/etc/default/mount-opts must be the one posted by sixwheeledbeast and NOT the rather simple default one (i.e. it should be one installed by CSSU-T).

It appears that there is at least one scenario, following a reflash and installation of CSSU-testing with an in-situ sd-card with 2 swap partitions, where a replacement mount-ops does not get installed. In such a case, /etc/event.d/rcS-late will generate 3 swaps in fstab and all can be made active (mounted). If flopswap is installed, with "swap to sd" enabled then the 2 sd-card swaps will show as active.

Thanks to "swb" for sticking with me.... (and for info added here)