I know what you mean about Renner being a Damon clone - they do look kinda similar (ish).
Regardless, though, does there really need to be any clear differentiation between Damon's Bourne and Renner's character? I don't really mind if Renner basically ends up playing Damon's Bourne by another name. I don't really enjoy these films for the Bourne character so much as for the atmosphere, suspense and action - I find them to be extremely well-crafted entertainments, but there's nothing really all that compelling about Bourne in and of himself when you get right down to it. Still, Damon always gives a very good performance in these flicks, which I'm sure Renner will also do. Whether or he not provides a markedly different lead character to Damon's Bourne is, for me, neither here nor there as long as he's good and the film is also good.