When looking from above at the lamp in the anisotropy example, it looks like this:
Is correct to have all that brightness?
The image is lit from above and over-exposed, but that doesn’t indicate anything necessarily incorrect. If you turn a metallic object to reflect light into the camera, you’ll get similar results. 
If you had a similar problem and were trying to solve it, you could (for example) adjust renderer.toneMappingExposure property to properly expose the image.