Nope, no extra reflection going on. As a note, in the real world, there isn't actually a difference between rough reflection and diffuse, it's all the same light being bounced from a surface (diffuse is just reflections that are scattered in all directions, the ultimate in rough reflections) - that said, it doesn't mean that Corona with just diffuse exhibits a greater "reflection like" look than other render engines (assuming those render engines are coded correctly).
So differences here most likely are the tonemapping, and as to the correctness of the unknown renderer, we can't say. Corona looks correct for what a diffuse only surface should look like under these conditions. And possibly GI, depending on how the other engine is handling it (if it is).