This does not seem like a particularly difficult question to answer to me, and I suspect it's because I'm not particularly precious about what it means to "be me."

The logical answer is that this spreadsheet, supposing identical mechanical processes - inputs, outputs, stored data - and I would both be convinced that they're "me", and they'd both be correct in that they'd both be something that functions, and therefore thinks, acts, and experiences things identically to me. Two different processes on different hardware running the same code. The concept of "ego" is a result of this code. To me, I'd be "me" and the spreadsheet would be "a copy of me". To the spreadsheet, it would be the exact opposite.

Of course, that predisposes that the software isn't hardware-dependent. But even then, I wouldn't discount the possibility of an emulation layer.

It really isn't hard once you accept that we're not special for being able to think about ourselves.