The previous value for an ON (to detect the it has
changed) is still suing a global value determined
at runtime so it can't store more than one of them,
which means multiple ON's from the same line of code
don't work right.  WHENs are working though.

On triggers' previous values are now tracked separately
merely by taking advantage of the local scoping
that was made available several months ago for triggers.

We just weren't using it because we still had the old code
that tried using the Global instead of Local storage Opcodes
in the trigger's boilerplate code blocks that tracked the
previous value.