I ran into this problem today. Here is how the problem occured:
1) I exported an already existing 3D object from a .dat library file. This object is composed of two meshes, the first one is UV-mapped for the main texture, and the second mesh is UV-mapped for the AO texture.
So, S3D exported two meshes at the same time: MMM.obj and MMM-uv2.obj.
2) Then, I opened both meshes in Wings3D in order to edge-split them.
3) Then, I exported both meshes as wavefront files (.obj) with the same name (MMM.obj and MMM-uv2.obj).
4) Then, I imported the meshes in S3D by importing MMM.obj (MMM-uv2.obj is detected automatically and imported at the same time).
And now the AO effect is broken... Like this:
I don't know how to fix that...
