Yes, but two BRKs in succession make little sense. The only reason to use that I can think of is as placeholders in self-modifying code. sta Routine_0c86 certa

Yes, but two BRKs in succession make little sense. The only reason to use that I can think of is as placeholders in self-modifying code. sta Routine_0c86 certainly is weird. It modifies the first byte of a subroutine. Again, that could be self-modifying code, but such a byte cannot be an immediate data byte or part of an address, making that less likely. Things like jsr $ffff also are weird. Why would there be a subroutine starting at the last addressable byte?