This is some extremely weird behavior. Basically, when multiple aumtlich beams are pointing at cracked orbs, weird things happen.
This hint thread covers a room that was meant to be based around this behavior, and includes what I was able to figure out about how it works:
-Aumtlich beams are processed in the move order of the aumtlich.
-When a new beam is processed, first it checks if that beam destroys any orbs. If it did, and another beam was blocked by that orb, that beam will effectively "
fire again"
, destroying any broken orbs in its path and turning cracked orbs into broken orbs.
-However, if the unblocked beam destroys any orbs and unblocks any other beams, those beams' effects (at least on orbs) will NOT be checked.
This last point, in particular, has weird consequences.
(The room in the linked hint thread has an unintended solution which should still work if the behavior is changed in a way which results in full chain reactions happening. I don't think any other rooms were made relying on the behavior, but I'm not entirely certain on that.)