Repro steps:
1) Open the project and ShaderArtifacts.scene
2) Switch platform to standalone Mac and change graphics API to OpenGL2
3) Notice in the back of the object strange writings (screenshot 1)
4) Switch platform to iOS
5) Turn off RotateAround script on GameObject
6) Rotate the shield so it's back would be seen (screenshot 2 position)
7) Build and run for lower-end device (iPad 2 f.e.)
8) Notice similar artifacts on the back of the shield

Expected behaviour is screenshot 3

Reproduced in: 5.4.0b14; 5.3.4p2; 5.2.4f1