@OtherRetroMatt I've just emailed the author about this.
@OtherRetroMatt it's kind of technically correct, but to most intents and purposes rather meaningless because the "approximations" are so close.
Also, during the lifecycle of a system, there are changes. Sound chips sound a little different, graphics chips work a little differently, etc... At times there's more of a difference between generations of real hardware than between an emulator and real hardware.