quoted

It looks more like the high level code that sets up these parameters
broke somehow and starts registering these twice and now ACPI is the
first one to hit it (maybe because it starts with 'a' :-). 

Perhaps we could try "acpi=off" and see if it still happens.

I doubt that would help because module_param()s are always registered
even with acpi=off. They are not really processed by ACPI, but by
kernel/params.c

-Andi