I’ll comment here, rather than in the main thread.
I’m skeptical of all of these information arguments.
As Durston describes it, he is measuring functional information based on the function of protein production. So he sees duplication as providing little additional information, since the same proteins are being produced.
From my way of looking at it, functional should be in terms of biological function – the ability of the organism to prosper and perhaps to deal with a change in environment. If duplication happens to enhance that biological viability, then could be a very important functional change.
I’m left with the concern that the argument is over a mathematical model, without a convincing accompanying argument about the applicability of the model. I’m reminded of Zeno’s paradox on the impossibility of motion.