This issue happens only with Instanced Stereo enabled.
You can replicate this by performing the following step
- Open the VR template.
- Delete all the light (this makes the problem more evident)
- Create a stationary light in front of the wall
- Put the gun on the other side of the wall
For example, you can refer to the following screenshot:
The shadow is cast on the gun in one eye only. This makes the weapon very bright in one eye and dark in the other.
Any idea how to fix this? This seems to be a bug.