Dark areas in baking process

Hello everyone,

I exported an OBJ file from CLO3D which had Udim and different materials that I separated on Blender. However, when I tried to bake the object, I noticed some dark areas. Upon further inspection, I realized that these dark areas were a result of Ambient Occlusion. It's worth mentioning that the dark areas were mostly present in places where there were double layers of "Fabric". Before baking, I set it to self-occlusion: with only the same mesh name. Please see the picture below. 

If you want the 3D object: 

https://drive.google.com/open?id=12nBUolrcsQ1umJ3RpDq05XD7IP8S8zv7&usp=drive_fs

Has anyone else encountered a similar problem?