There would be no way to find out if that would be true however. The person in the vat might say they are the same person but you don't know if they really are. Also what happens if you create a copy? Is that two people or is there some kind of shared consciousness? If it is, how do they communicate?
Boy am I glad I replaced stock firmware with OpenWRT the moment my router came out of box last week. It was also extremely painless experience, and I'd really recommend people to buy routers with OpenWRT support, even if they cost a little more. A router is something you buy for a decade or more, and it's worth the investment. Our livelihood depends on network availability, and depending on whims of terrible router firmware is not something to rely on.