From the global point of view, you only consider different possible experiences, that imply different possible situations. Nothing changes, because everything is determined from the global viewpoint. If you want to determine certain decisions in response to certain possible observations, you also specify that globally, and set it in stone. Whatever happens to you, you can (mathematically speaking) consider that in advance, as an input sequence to your cognitive algorithm, and prepare the plan of action in response. The fact that you participate in a certain mind-copying experiment is also data to which you respond in a certain way.

This is of course not for human beings, this is for something holding much stronger to reflective consistency. And in that setting changing preferences is unacceptable.