A claim that a big effect from "mutation" makes "new information" irrelevant Pt.2

I have a second response to that thread at EvC I discussed in the previous post. That is, if we assume, as the evolutionists do, that humans did descend from previous life forms -- my main objection in that post was that their holding this assumption amounts to begging the question -- but if we accept their assumption for argument's sake, then perhaps we can entertain the possibility that this is an example of a difference humans have from those ancestors that didn't involve the acquisition of new genetic information.

If I take that as my premise then I have questions: Here is where I really need better description or a picture of what is meant by this "duplicate" gene, how it appears on the DNA strand and so on. My main question would then be, has this sort of change ever been seen within a species? I mean, I've seen many discussions and diagrams of different ways mutations occur and the complete duplication of a gene is not one I've ever seen.

Another question is, of course, that even if this particular human trait did evolve from some animal form, but didn't involve the acquisition of new genetic information, what about all the other differences between humans and animals? We'd need to list them and think about whether it would have been necessary that new genetic information be acquired for each supposedly evolved change to have occurred.