Are you sure that's not a disproof of design?
I am positive. A Creator would have no problem at all making each species a little bit differently. Evolution on the other hand would have a big problem making each gene different in each species. For one thing it takes a lot of evolutionary time to do so, for another, why should it? If it works, what reason would there be according to "survival of the fittest" to change it? None at all.
Obviously a Creator can do anything, but why would He make each gene different if, as you claim, there's a single optimum? (Hint number one: there isn't.)
Wouldn't it be more like a design if there were a single, standard gene for cytochrome c or hemoglobin? Wouldn't it be less like an accident if functional genes like Vitamin C weren't turned off but still sitting there taking up space in the primate genome?
No, nothing ever, ever disproves design. But you have stumbled onto a point against it, one that molecular biologists notice all the time. Molecular clocks are out there, running. Design does not predict this. Design does not predict anything.