Note that you said "this spreadsheet and I", meaning that there is something particularly precious about the current "I". You don't think that you'd suddenly become the spreadsheet, "detaching" (can't find a better word) from your existing body. You intrinsicly assume that the spreadhseet would remain a third person from "your" perspective, even though it's a perfect replica.

I don't follow? I can copy a file and then consider the two files to be separate copies of the same data?

What should I have said instead? "We"? "Him and it"? Self-modeling is part of my experience. I'm sure it'll be part of the spreadsheet's experience as well, if it functions identically to me.

I don't see the gotcha at all?