It doesn't surprise me at all that Lance doesn't recognise Ollie, because his suspicion was based on Ollie and The Vigilante appearing in the city at the same time, not on appearance. I think it is being pushed to the edge of believability now because Ollie is connected to both Sara and Felicity, but Lance had to break his commitment to the idea and rationalize his "error." Now he has a commitment to the new idea.
But if Lance knew that Oliver is the Arrow would he feel compelled to arrest him?
Or has the fact that he's even called the arrow and knows that he's working with Sarah taken him beyond that point?
The fact that he has been working with him for most of season 2 seems to indicate he has gotten over his hatred of the Arrow.