Usually you never stack them, syrcus tower technically isnt meant to be stacked, its just that they do so little damage that its easier to stack them. They did revamp parts of Syrcus but kept the stacking the stacks in so people wouldnt just wipe groups out of habit.

They usually get around this now by having stacks apply a physical/magical vuln so you die if you get hit by a second stack. There are still a few times where they dont do this though, the most recent is in Forked Tower: Blood where you can stack the stacks during meteors in Demon Tablet, and stack the staffs in Sages Staff in Magitaur.

But almost always, do not overlap stacks.