Lightmapping Question (713555)

Hello All,
I have been working with the lightmapping settings for some time now, and I am continually encountering a strange issue which I cannot seem to track down, nor have I yet found a past forum thread about the same issue.

Quite simply, when I am baking my lightmaps, sometimes two of the same object will respond differently to the bake. Observe the tiled floor by the door in the shot attached.


As you can see, the tile object to the right is much lighter colored than its left hand counterpart. The tiles are duplicates of one another. They contain no difference in settings and are both rendered from the same mesh. As of yet I have found no way to get them to bake consistently.

For starters I have tried clearing cache, rebaking many times, recalculating normals, and checking all their mesh renderer settings for differences

Any thoughts on what this might be caused by?

Are the tiles seperate geometry?
Normally I would suspect different light conditions / sampling to be the problem have you tried baking only with constant Ambient Light (color) e.g. turning all lights off?

They are separate geometry. I have tried baking with only ambient light and a similar thing occurs.