1. Is there a sun present in that HDRI? If so, then the left one could be the correct result.
2. Is there a Corona Sun object in your scene? If so, then it might cause the rendering to look like the left one. Maybe it is hidden? Or on a different layer? Is it listed when you press H?
Update: if this started happening after switching from Corona 1 to 1.2+, then this is most probably sun issue, though it shouldn't be happening any more.