Not sure why you're getting downvotes. Sure, the argument comes off as sort of sophomoric in the face of the indisputable fact that there was an actual Rembrandt and this painting was produced neither by him nor by a low-fidelity replica of his brain; but I think it's interesting to think about. If we wanted to get real sophomoric, we'd apply the Ship of Theseus/Heraclitus/Lucretius line of thought to whether even a Rembrandt is a Rembrandt: is what I made yesterday made equally by the me of today? Cross-pollinating the brain-replication discussion with the multiverse discussion is pretty wild to think about: what is a copy of a dynamic thing?