**System Information**
Operating system: Windows 10 64 Home
Graphics card: GTX 1080Ti
**Blender Version**
Broken: Version 2.80 Beta e7356bb01198, 2019-07-02 13:31
**FBX exporter apply 'remove doubles' and change the vertex normals of the surface.**
**Exact steps for others to reproduce the error**
Based on the default startup of Blender 2.8 export FBX with both ‘normals only’ and ‘edge’ smoothing, both gives identical bug:
The FBX exporter is recalculating **custom** normals or applying to remove double vertices when exporting.
For example, the OBJ instead is working fine.
Consider in the FBX user interface a boolean to toggle it off (so that vertex normals are preserved).